Progress of millisecond and nanosecond laser in-situ direct synthesis nitriding(LIDN) was introduced. LIDN titanium and its alloy were reviewed intensively, and the recent works about geometry parameters, structures and mechanical properties influenced by laser intensity and nitrogen concentration were also summed up. Numerical model of crack led by secondary effect of gradient temperature and stress field were also concerned in these studies. Future works of LIDN and the possible technique were proposed bo...