diff --git a/README.md b/README.md
index 5f51d95..50e42af 100644
--- a/README.md
+++ b/README.md
@@ -1 +1,34 @@
 # PedstrianPrediction
+
+This repo re-implement social LSTM and implement a new Spatial Pyramid Social LSTM proposed by us.  
+This implementation is based on [https://github.com/vvanirudh/social-lstm-tf](https://github.com/vvanirudh/social-lstm-tf). We fix several bugs and vital errors in their repo. We also upgrade the tensorflow API to 1.8.0.
+
+## File Structure
+### data
+- `getPixelCoordinates.m`: the matlab code to transform original ETH dataset to `pixel_pos.csv`, which is used in our code. This file is based on the referred implementation.
+- `pixel_pos.csv`: the data file used by our code
+- `transformed_data.pkl`: `pixel_pos.csv` will be transformed in our code and save as transformed_data.pkl
+
+### social_lstm
+- `DataLoader.py`: deal with data loading and preprocess
+- `grid.py`: calculate grid or pyramid mask, called by `train.py`
+- ***`model.py`***: IMPORTANT! all model (including social lstm and spatial pyramid social lstm) are defined here
+- ***`social_sample.py`***: predict/test code, could be called using proper console parameters (use `social_sample.py --help` to see)
+- `social_visualize.py`: to draw predicted graphs
+- ***`train.py`***: train code, could be called using proper console parameters (use `train.py --help` to see)
+
+#### plot
+This directory contains several prediction plots for "Spatial Pyramid Social LSTM" method. 
+Other method's plot can't be obtained since lab server is under maintenance (explained in our report). 
+
+#### save
+This directory contains model file for "Spatial Pyramid Social LSTM" method. 
+Other method's model can't be obtained since lab server is under maintenance (explained in our report). 
+
+## Usage
+1. delete everything under `social_lstm/save/`
+2. run `train.py` to train a model
+3. run `social_sample.py` to predict
+4. run `social_visualize.py` to visualize
+
+## Authored by Letian Chen & Tianyang Zhao
\ No newline at end of file