An　underactuated　AUV　non-singular　fast　integrating　terminal　sliding　mode　controller　with　input　saturation　constraint　and　external　disturbance　is　proposed.　Firstly,　the　desired　longitudinal　velocity　and　expected　yaw　rate　are　obtained　by　the　line-of-sight　guidance　method.　Aiming　at　the　velocity　tracking　errors　and　angular　velocity　tracking　errors,　a　trajectory　tracking　controller　is　designed　by　using　the　non-singular　fast　integrating　terminal　sliding　mode　control　method.　The　adaptive　RBF　neural　network　is　used　to　approximate　unknown　time-varying　disturbances　and　the　time　derivatives　of　desired　velocity.　A　kind　of　anti-windup　controller　is　designed　to　solve　the　actuator　saturation　problem.　Numerical　simulation　shows　that　the　proposed　controller　is　robust　to　external　disturbance　and　can　handle　the　input　saturation　effect　well.　©　2023　Editorial　office　of　Ship　Building　of　China.　All　rights　reserved.