1. My instructor recommended me. There are many competitions and high specifications. Most of them are graduate instructors leading the team to participate:
MARS Data Science Platform
https://www.marsbigdata.com/
2. Hewhale community
https://www.kesci.com/
3. Aliyun Tianchi
https://tianchi.aliyun.com/
4. Baidu Star
https://star.baidu.com
5. I love competition network
www.52jingsai.com/
6. Saikr network
http://www.saikr.com/
7.datafountain
https://www.datafountain.cn/