We　propose　a　gain　control　method　for　acousto-optic　Q-switched　lasers.　The　laser　in　single-pulse　mode　can　be　converted　into　a　double-pulse　mode　with　adjustable　subpulse　intervals　and　energy　ratios.　It　reduces　the　peak　energy　density　while　keeping　the　total　energy　unchanged　in　a　cycle　and　thus　effectively　avoids　damage　to　the　optical　fiber.　The　gain　of　the　beam　can　be　controlled　by　modulating　the　diffraction　loss　in　the　resonant　cavity.　A　theoretical　model　of　acousto-optic　Q-switched　double-pulse　laser　is　established.　Double-pulsing　with　adjustable　subpulse　intervals　and　energy　ratios　can　be　designed.　A　double-pulse　laser　is　built　experimentally,　and　the　actual　output　waveform　is　basically　consistent　with　the　calculated　results　of　the　theoretical　model.　A　double-pulse　laser　with　adjustable　energy　ratios,　adjustable　subpulse　intervals　of　500　ns-20　mu　s,　and　127　W　at　5　kHz　can　be　obtained.　In　addition,　laser　paint　removal　experiments　are　conducted,　proving　that　the　double-pulse　laser　has　the　same　cleaning　ability　as　the　single-pulse　laser　at　the　same　average　output　power.　At　the　same　time,　the　damage　to　the　optical　fiber　can　be　largely　avoided.