diff --git a/official/cv/ctpn/train.py b/official/cv/ctpn/train.py
index ca8085beb84958c2a4016c35b5877a63b79b0733..df3617848bd7cc6f6cbb707f674afa1862364ced 100644
--- a/official/cv/ctpn/train.py
+++ b/official/cv/ctpn/train.py
@@ -45,7 +45,7 @@ context.set_context(mode=context.GRAPH_MODE, device_target=config.device_target,
     device_id=get_device_id(), save_graphs=True)
 
 # Set mempool block size in PYNATIVE_MODE for improving memory utilization, which will not take effect in GRAPH_MODE
-context.set_context(mempool_block_size="31GB")
+context.set_context(mempool_block_size="20GB")
 
 binOps = {
     ast.Add: operator.add,