QS University Ranking 2017 by Math Subject

Top 5:

1. MIT
2. Harvard
3. Stanford
4. Oxford
5. Cambridge

18 University of Tokyo
…
20 Peking University 北京大学
…
22 Ecole Polytechnique (France)
…
26 TsingHua University 清华大学
…
28 Hong Kong University
…
32 Ecole Normale Supérieure (Paris)

https://www.theguardian.com/education/2017/mar/08/qs-world-university-rankings-2017-mathematics