diff --git a/.github/workflows/ci-cuda.yml b/.github/workflows/ci-cuda.yml
index e1614f0f65b40c118dd3e4b15d76c19254470d5b..e643bcb323731040e6bd1320c5a8662056a22c92 100644
--- a/.github/workflows/ci-cuda.yml
+++ b/.github/workflows/ci-cuda.yml
@@ -13,6 +13,8 @@ jobs:
       volumes:
         - /usr/local/cuda-10.1-libs:/usr/local/cuda-10.1-libs
       options: --gpus all --shm-size 1g
+      env:
+        NCCL_LAUNCH_MODE: PARALLEL
 
     steps:
       - name: Checkout MegEngine