diff --git a/CHANGELOG.md b/CHANGELOG.md
index da6a08fff36..206b98eca33 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -109,6 +109,7 @@ We use *breaking :warning:* to mark changes that are not backward compatible (re
 - [#6519](https://github.com/thanos-io/thanos/pull/6519) Reloader: Use timeout for initial apply.
 - [#6509](https://github.com/thanos-io/thanos/pull/6509) Store Gateway: Remove `memWriter` from `fileWriter` to reduce memory usage when sync index headers.
 - [#6556](https://github.com/thanos-io/thanos/pull/6556) Thanos compact: respect block-files-concurrency setting when downsampling
+- [#6539](https://github.com/thanos-io/thanos/pull/6539) Store : Changed `--sync-block-duration` default 3m to 15m.
 - [#6592](https://github.com/thanos-io/thanos/pull/6592) Query Frontend: fix bugs in vertical sharding `without` and `union` function to allow more queries to be shardable.
 - [#6317](https://github.com/thanos-io/thanos/pull/6317) *: Fix internal label deduplication bug, by resorting store response set.
 - [#6189](https://github.com/thanos-io/thanos/pull/6189) Rule: Fix panic when calling API `/api/v1/rules?type=alert`.
diff --git a/cmd/thanos/store.go b/cmd/thanos/store.go
index 73e4b838ddc..51491106b82 100644
--- a/cmd/thanos/store.go
+++ b/cmd/thanos/store.go
@@ -132,7 +132,7 @@ func (sc *storeConfig) registerFlag(cmd extkingpin.FlagClause) {
 	sc.objStoreConfig = *extkingpin.RegisterCommonObjStoreFlags(cmd, "", true)
 
 	cmd.Flag("sync-block-duration", "Repeat interval for syncing the blocks between local and remote view.").
-		Default("3m").DurationVar(&sc.syncInterval)
+		Default("15m").DurationVar(&sc.syncInterval)
 
 	cmd.Flag("block-sync-concurrency", "Number of goroutines to use when constructing index-cache.json blocks from object storage. Must be equal or greater than 1.").
 		Default("20").IntVar(&sc.blockSyncConcurrency)
diff --git a/docs/components/store.md b/docs/components/store.md
index 26b359f3267..e191f60578d 100644
--- a/docs/components/store.md
+++ b/docs/components/store.md
@@ -204,7 +204,7 @@ Flags:
                                  The maximum series allowed for a single Series
                                  request. The Series call fails if this limit is
                                  exceeded. 0 means no limit.
-      --sync-block-duration=3m   Repeat interval for syncing the blocks between
+      --sync-block-duration=15m   Repeat interval for syncing the blocks between
                                  local and remote view.
       --tracing.config=<content>
                                  Alternative to 'tracing.config-file' flag