Traditional sculling algorithms make use of incremental output of gyros and accelerometers to design algorithms, when they are applied to fiber-optical gyro strap down inertial system, the incremental signals should be simulated by angular rate, which not only increases design difficulty but also reduce calculation accuracy. In view of this, an improved sculling algorithm was proposed, which made use of angular rate/specific force signal directly, and the error formula was derived in the condition of sculling input. Theoretical deduction and simulation results indicate that the precision of improved algorithms is far superior to that of traditional ones.