diff --git a/tools/make_test_data.py b/tools/make_test_data.py
index d99650c1..fd2a5995 100755
--- a/tools/make_test_data.py
+++ b/tools/make_test_data.py
@@ -84,7 +84,9 @@ def make_test_data(name, meter_type, unit, volume, random_min,
                           )
         data = utils.meter_message_from_counter(
             c, cfg.CONF.publisher.telemetry_secret)
-
+        # timestamp should be string when calculating signature, but should be
+        # datetime object when calling record_metering_data.
+        data['timestamp'] = timestamp
         yield data
         n += 1
         timestamp = timestamp + increment
diff --git a/tools/send_test_data.py b/tools/send_test_data.py
index d401f80c..ed9b9f59 100755
--- a/tools/send_test_data.py
+++ b/tools/send_test_data.py
@@ -83,6 +83,10 @@ def generate_data(send_batch, make_data_args, samples_count,
         resource = resources_list[random.randint(0, len(resources_list) - 1)]
         resource_samples[resource] += 1
         sample['resource_id'] = resource
+        # need to change the timestamp from datetime.datetime type to iso
+        # format (unicode type), because collector will change iso format
+        # timestamp to datetime.datetime type before recording to db.
+        sample['timestamp'] = sample['timestamp'].isoformat()
         # need to recalculate signature because of the resource_id change
         sig = utils.compute_signature(sample,
                                       cfg.CONF.publisher.telemetry_secret)