In 1993, he completed his PhD under the direction of Yum-Tong Siu with thesis Global nondeformability of the complex hyper quadric.

[1] He was in 2006 an invited speaker with talk Rigidity of rational homogeneous spaces at the International Congress of Mathematicians (ICM) in Madrid[5] and in 2014 a plenary speaker with talk Mori geometry meets Cartan geometry: Varieties of minimal rational tangents at the ICM in Seoul.

[6] With his collaborator Ngaiming Mok, he has developed the theory of varieties of minimal rational tangents, which combines methods of algebraic geometry and differential geometry in the study of rational curves on algebraic varieties.

He has applied this theory to settle a number of problems on algebraic varieties covered by rational curves.

[1]In 2020, he was the founding director of the Center for Complex Geometry at the Institute for Basic Science.