Kinetic weapon attack targets underwater with small range operations, short time features at the end of the time. Traditional linear sliding mode control guidance law can not meet the system in a finite time fast conver- gence to equilibrium requirements, that can not ensure attacking the target effectively. To solve the problem, this paper proposes an improved Terminal Sliding Mode Control method, guarantee system convergence to equilibrium state in finite time, by introducing nonlinear factor, make the system tracking error converge to zero quickly. By combining with exponential reaching law Terminal sliding mode surface design limited time fast convergent guidance law. The guidance law can ensure that the system convergence to equilibrium fast and calculate convergence time off-line. Theoretical analysis, the designed guidance law can meet the requirements of the system＇s stability, and its effectiveness was verified through simulation, and its convergence time is faster than traditional variable structure guidance law, has stronger robustness.