Quantum communication is the current research frontier and hotspot in quantum field. The gain-switched semiconductor laser generation technology is a relatively mature method to generate pulsed laser, and can meet the demand for pulsed laser in quantum communication when it is combined with the injection-locking technology. This article systematically introduces the working principle of gain-switched semiconductor lasers, injection-locking schemes, and their applications in quantum key distribution, quantum random number generation, etc. The relevant physical principles, experimental schemes, and recent progress are emphasized, and a brief outlook on the development in the future is finally given.