diff --git a/federatedscope/trafficflow/dataloader/traffic_dataloader_v2.py b/federatedscope/trafficflow/dataloader/traffic_dataloader_v2.py
index 84f6df0..98c5f56 100644
--- a/federatedscope/trafficflow/dataloader/traffic_dataloader_v2.py
+++ b/federatedscope/trafficflow/dataloader/traffic_dataloader_v2.py
@@ -89,7 +89,6 @@ def load_traffic_data(config, client_cfgs):
     root = config.data.root
     dataName = 'PEMSD' + root[-1]
     raw_data = load_st_dataset(dataName)
-    sub_graph_size = config.model.minigraph_size
 
     l, n, f = raw_data.shape