diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000000000000000000000000000000000000..513581d3278bbcc6c68a4196ea767b794cf736af
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "demo/pytorch-CycleGAN-and-pix2pix"]
+	path = demo/pytorch-CycleGAN-and-pix2pix
+	url = https://github.com/Superjomn/pytorch-CycleGAN-and-pix2pix.git
diff --git a/demo/README.md b/demo/README.md
new file mode 100644
index 0000000000000000000000000000000000000000..08ca00aa7853d3f84f97e1bbe9514923a75b36ac
--- /dev/null
+++ b/demo/README.md
@@ -0,0 +1,27 @@
+# VisualDL demos
+
+VisualDL supports Python and C++ based DL frameworks, 
+there are several demos for different platforms.
+
+## PaddlePaddle
+Locates in `./paddle`.
+
+This is a visualization for `resnet` on `cifar10` dataset, we visualize the CONV parameters, 
+and there are some interesting patterns.
+
+## PyTorch GAN
+Locates in `./pytorch-CycleGAN-and-pix2pix`.
+
+This submodule is forked from [pytorch-CycleGAN-and-pix2pix](
+https://github.com/junyanz/pytorch-CycleGAN-and-pix2pix), 
+great model and the generated fake images are really funny.
+
+This demo only works with CycleGAN mode, read [CycleGAN train doc](https://github.com/Superjomn/pytorch-CycleGAN-and-pix2pix#cyclegan-traintest) and [changes to the original code](https://github.com/junyanz/pytorch-CycleGAN-and-pix2pix/compare/master...Superjomn:master) for more information.
+
+## MxNet Mnist
+Locates in `./mxnet_demo`.
+
+By adding VisualDL as callbacks to `model.fit`, 
+we can use the Python SDK in MxNet, 
+but it seems that only the outside program can only retrieve parameters in epoch callbacks,
+that limits the number of steps for visualization.
diff --git a/demo/pytorch-CycleGAN-and-pix2pix b/demo/pytorch-CycleGAN-and-pix2pix
new file mode 160000
index 0000000000000000000000000000000000000000..1f8ed8767802e1aea667c4a760a77be7146b916f
--- /dev/null
+++ b/demo/pytorch-CycleGAN-and-pix2pix
@@ -0,0 +1 @@
+Subproject commit 1f8ed8767802e1aea667c4a760a77be7146b916f
diff --git a/tests.sh b/tests.sh
index c468f0034b69c047c517ddd6a08b7395681ae8ee..8f9d7807012d9183cba3e467c65014097c2df802 100644
--- a/tests.sh
+++ b/tests.sh
@@ -79,8 +79,8 @@ bigfile_reject() {
     cd $TOP_DIR
     # it failed to exclude .git, remove it first.
     rm -rf .git
-    local largest_file="$(find . -path .git -prune -o -printf '%s %p\n' | sort -nr | head -n1)"
-    local size=$(echo $largest_file | awk '{print $1}')
+    local largest_file=$(find . -path .git -prune -o -printf '%s %p\n' | sort -nr | grep -v "CycleGAN"| head -n1)
+    local size=$(echo "$largest_file" | awk '{print $1}')
     if [ "$size" -ge "$max_file_size" ]; then
         echo $largest_file
         echo "file size exceed $max_file_size"