The invention discloses a light weapon and a use method thereof. The light weapon comprises a fixing shell. A closed cavity is formed in the fixing shell, an ammunition cavity with an upward opening is arranged inside the fixing shell, and a compression spring is fixedly connected with the lower end wall of the ammunition cavity. A placing platform is fixedly connected with the upper end face of the compression spring, a driving space is arranged inside the left end wall of the ammunition cavity, and a driving motor is fixedly arranged on the upper end wall of the driving space. A fire cap isfixedly arranged on the lower side of the interior of an ignition cavity, and a blasting fuse is fixedly connected with the lower end face of the fire cap. According to the light weapon and the use method thereof, the structure is simple, operation is convenient, stability of the transmission process is ensured through gear transmission and belt transmission, and link switching is realized by adopting a spline to be connected in a fit mode, thus flexibility of use is enhanced, meanwhile, safety of the equipment is enhanced, and interference of external factors is avoided; and a grenade and a magazine are combined organically, and thus survival probability of warfighters is improved.