Abstract: A gain-switched Cr4+:Mg2SiO4 laser pumped by a 1.06μm Q-switched laser pulse with lower energy is investigated.By numerically solving the rate equations and choosing the suitable initial conditions,the temporal profile of the(1.22μm) laser pulse is obtained.Simultaneously the relations of the buildup time and the pulse-duration of the 1.22μm laser with the pump energy are achieved respectively and the theoretical and experimental results basically coincide with each other.When the energy and the pulse-duration of the pump laser pulse are 45mJ and 30ns respectively,a 1.22μm laser pulse is achieved with the energy of 7mJ and the pulse-duration of 8.2ns.The pulse-duration of the output laser is nearly a quarter of that of the pump laser and the transfer efficiency is 15.5%.The numerical calculation and the experimental results show that both the buildup time and pulse-duration decreased as the pump energy increasing.