diff --git a/regression-test/suites/compaction/test_time_series_compaction_policy.groovy b/regression-test/suites/compaction/test_time_series_compaction_policy.groovy
index 7f3aa2abf81770..b970926c93b079 100644
--- a/regression-test/suites/compaction/test_time_series_compaction_policy.groovy
+++ b/regression-test/suites/compaction/test_time_series_compaction_policy.groovy
@@ -36,6 +36,34 @@ suite("test_time_series_compaction_polciy", "p0") {
         return rowsetCount
     }
 
+    // Manually POST cumulative compaction to every tablet. Fire-and-forget;
+    // per-tablet errors (e.g. CUMULATIVE_NO_SUITABLE_VERSION on a tablet with
+    // nothing to merge) are expected and surface via the polling assertion.
+    def trigger_cumulative_all = { tabletsList ->
+        for (def tablet in tabletsList) {
+            def be_host = backendId_to_backendIP["${tablet.BackendId}"]
+            def be_port = backendId_to_backendHttpPort["${tablet.BackendId}"]
+            curl("POST", "http://${be_host}:${be_port}/api/compaction/run?tablet_id=${tablet.TabletId}&compact_type=cumulative")
+        }
+    }
+
+    // Poll get_rowset_count until count <= target or timeout. Returns the last
+    // observed count. Avoids the run_status race in trigger_and_wait_compaction
+    // for time_series mode (BE may have queued the task but not yet acquired
+    // the cumulative lock when first polled).
+    def wait_rowset_count_le = { tabletsList, target, timeoutSec ->
+        long deadline = System.currentTimeMillis() + timeoutSec * 1000
+        int last = -1
+        while (System.currentTimeMillis() < deadline) {
+            last = get_rowset_count.call(tabletsList)
+            if (last <= target) {
+                return last
+            }
+            Thread.sleep(1000)
+        }
+        return last
+    }
+
     sql """ DROP TABLE IF EXISTS ${tableName}; """
     sql """
         CREATE TABLE ${tableName} (
@@ -133,21 +161,19 @@ suite("test_time_series_compaction_polciy", "p0") {
     assert (rowsetCount == 34 * replicaNum)
 
     // trigger cumulative compactions for all tablets in table
-    trigger_and_wait_compaction(tableName, "cumulative")
-
     // after cumulative compaction, there is only 26 rowset.
     // 5 consecutive empty versions are merged into one empty version
     // 34 - 2*4 = 26
-    rowsetCount = get_rowset_count.call(tablets);
-    assert (rowsetCount == 26 * replicaNum)
+    trigger_cumulative_all.call(tablets)
+    rowsetCount = wait_rowset_count_le.call(tablets, 26 * replicaNum, 60)
+    assert (rowsetCount == 26 * replicaNum) : "expected ${26 * replicaNum} rowsets, got ${rowsetCount}"
 
     // trigger cumulative compactions for all tablets in ${tableName}
-    trigger_and_wait_compaction(tableName, "cumulative")
-
     // after cumulative compaction, there is only 22 rowset.
     // 26 - 4 = 22
-    rowsetCount = get_rowset_count.call(tablets);
-    assert (rowsetCount == 22 * replicaNum)
+    trigger_cumulative_all.call(tablets)
+    rowsetCount = wait_rowset_count_le.call(tablets, 22 * replicaNum, 60)
+    assert (rowsetCount == 22 * replicaNum) : "expected ${22 * replicaNum} rowsets, got ${rowsetCount}"
 
     qt_sql_2 """ select count() from ${tableName}"""
     if (isCloudMode()) {
@@ -156,11 +182,10 @@ suite("test_time_series_compaction_polciy", "p0") {
     sql """ alter table ${tableName} set ("time_series_compaction_file_count_threshold"="10")"""
     sql """sync"""
     // trigger cumulative compactions for all tablets in ${tableName}
-    trigger_and_wait_compaction(tableName, "cumulative")
-
     // after cumulative compaction, there is only 11 rowset.
-    rowsetCount = get_rowset_count.call(tablets);
-    assert (rowsetCount == 11 * replicaNum)
+    trigger_cumulative_all.call(tablets)
+    rowsetCount = wait_rowset_count_le.call(tablets, 11 * replicaNum, 60)
+    assert (rowsetCount == 11 * replicaNum) : "expected ${11 * replicaNum} rowsets, got ${rowsetCount}"
     qt_sql_3 """ select count() from ${tableName}"""
 
     sql """ DROP TABLE IF EXISTS ${tableName}; """