diff --git a/config.toml.dist b/config.toml.dist
index 67a4a9f..290bbd2 100644
--- a/config.toml.dist
+++ b/config.toml.dist
@@ -1,7 +1,17 @@
 # begin time of statistics period. 
-# for merged PRs, we only analysis those being merged after begin time.
-# for open PRs, we only analysis those being created after begin time.
+# for merged PRs, we only analysis those being merged after begin time (begin time included).
+# for open PRs, we only analysis those being created after begin time(begin time included).
+# if begin time not specified, it defaults to create time(merge time) of the very first PR. 
+# this usually will result in listing all PRs of specified repository and slow analysis process.
 statBeginTime = 2016-10-01T00:00:00
+
+# end time of statistics period. 
+# for merged PRs, we only analysis those being merged before end time (end time excluded).
+# for open PRs, we only analysis those being created after end time(end time excluded).
+# if end time not specified, it defaults to current time.
+# if end time is specified, week statistics is disabled.
+statEndTime = 2016-10-01T00:00:00
+
 accessToken = "personal access token"
 
 # repositories in which Pull Requests / Commits are analyzed
diff --git a/githubstat/load.go b/githubstat/load.go
index e941d83..22f6ece 100644
--- a/githubstat/load.go
+++ b/githubstat/load.go
@@ -1,7 +1,6 @@
 package githubstat
 
 import (
-	"fmt"
 	"time"
 
 	"github.com/BurntSushi/toml"
@@ -23,6 +22,7 @@ type User struct {
 }
 type Configuration struct {
 	StatBeginTime    time.Time
+	StatEndTime      time.Time
 	AccessToken      string
 	Users            []User
 	Repos            []string
@@ -47,12 +47,12 @@ func getWeekFirstDay(t time.Time) time.Time {
 }
 
 // read config file
-var _ = func() int {
+func init() {
 	if _, err := toml.DecodeFile("./config.toml", &Config); err != nil {
 		panic(err)
 	}
+	if !Config.StatEndTime.After(Config.StatBeginTime) {
+		panic("stat end time must be after stat begin time")
+	}
 	Config.ThisWeekFirstDay = getWeekFirstDay(time.Now())
-	fmt.Printf("this week first day is : %v\n", Config.ThisWeekFirstDay)
-	fmt.Printf("stat begin time is : %v\n", Config.StatBeginTime)
-	return 0
-}()
+}
diff --git a/githubstat/metrics_pull_request.go b/githubstat/metrics_pull_request.go
index 622c6e1..b7878fa 100644
--- a/githubstat/metrics_pull_request.go
+++ b/githubstat/metrics_pull_request.go
@@ -33,6 +33,10 @@ func (w *WeekPullRequestMetrics) merge() {
 
 }
 func (w *WeekPullRequestMetrics) Show() {
+	if !Config.StatEndTime.IsZero() {
+		fmt.Println("Week statistics is disabled because statEndTime is specified")
+		return
+	}
 	w.merge()
 	data := [][]string{}
 	var totalMerged int
@@ -55,7 +59,7 @@ func (w *WeekPullRequestMetrics) Show() {
 	}
 	if len(data) != 0 {
 		table := tablewriter.NewWriter(os.Stdout)
-		fmt.Print("\nStatistics Per Week\n")
+		fmt.Printf("\nStatistics for this Week ( week first day : %v)\n", Config.ThisWeekFirstDay)
 		table.SetHeader([]string{"User Name", "Merged PRs", "Merged Commits",
 			"LGTM'ed PRs", "NonLGTM'ed PRs", "Created PRs"})
 		table.AppendBulk(data)
@@ -117,7 +121,7 @@ func (m *OverallPullRequestMetrics) Show() {
 	}
 	if len(data) != 0 {
 		table := tablewriter.NewWriter(os.Stdout)
-		fmt.Print("\nOverall Statistics\n")
+		fmt.Printf("\nOverall Statistics ( %v ~ %v)\n", Config.StatBeginTime, Config.StatEndTime)
 		mergedCommitsHeader := "Merged Commits(actual/stack)"
 		table.SetHeader([]string{"User Name", "Merged PRs", mergedCommitsHeader, "LGTM'ed PRs", "NonLGTM'ed PRs"})
 		table.AppendBulk(data)
@@ -238,6 +242,9 @@ loop:
 		fmt.Printf("page:%d fin\n", page)
 		for _, pr := range prs {
 			t := pr.CreatedAt
+			if !Config.StatEndTime.IsZero() && !t.Before(Config.StatEndTime) {
+				continue
+			}
 			if !t.Before(Config.StatBeginTime) {
 				allPRs = append(allPRs, pr)
 			} else {
@@ -274,17 +281,19 @@ loop:
 
 		fmt.Printf("page:%d fin\n", page)
 		for _, pr := range prs {
+
 			if pr.MergedAt == nil {
 				continue
 			}
 			t := pr.UpdatedAt
-
 			/*
 				MergedAt is always before UpdatedAt, so if a PR is updated before stat begin time,
 				this PR is absolutely merged before stat begin time.
+				WARNING: UpdatedAt is sorted descendingly, but MergedAt is not. so we can break outer loop according to MergedAt
 			*/
 			if !t.Before(Config.StatBeginTime) {
-				if !pr.MergedAt.Before(Config.StatBeginTime) {
+
+				if !pr.MergedAt.Before(Config.StatBeginTime) && !Config.StatEndTime.IsZero() && pr.MergedAt.Before(Config.StatEndTime) {
 					allPRs = append(allPRs, pr)
 				}