Under the condition of high dynamic angular motion or vibration environment, confirmed and corrected the sculling error was important to calculate the speed of strapdown inertial system In general, traditional velocity algorithms of strapdown inertial system used increment angular signals of gyroscopes and velocity increment signals of accelerometers. While on condition that the outputs of FOG were angular rate signals. So traditional algorithms were not suitable for FOG strapdown systems. In this paper, a new sculling compensation algorithm was proposed and optimized and the expression of sculling error of this algorithm was derived. Simulations are performed which indicate that the improved algorithm is more accurate than those traditional ones.