In order to study the effects of laser shock with ultra-high strain rate on the warm forming properties of magnesium alloy, experimental research and simulation analysis of laser shock forming (LSF) and warm laser shock forming (WLSF) at 200 ℃ are carried out on AZ31 alloy sheets with Nd: glass laser with power density of 1.53 GW/cm2 and pulse width of 20 ns. The results show that AZ31 alloy sheets have good WLSF ability with ultrahigh strain rate and can achieve double effsect of warm forming and modification. High value residual compressive stress and high density dislocations are generated on the surfaces of the samples. Residual compressive stress induced by WLSF is more stable than that induced by LSF. The laser shock with the ultra-high strain rate and dynamic recrystallization may contribute to the formation of nano-grains. Surface morphology and roughness and surface residual stress distribution of LSF and WLSF samples are also analyzed.