Abstract: According to the defect of traditional CORDIC algorithm on calculating arcsine and arccosine function,an improved algorithm is proposed,which uses double rotations with a constant factor and partial direction prediction. The modeling and fixed-point simulation is implemented on MATLAB platform,while the hardware realization is done on FPGA with a pipeline structure.The speed of this IP core reaches 192 M Hz and the average error is less than 10-4.This algorithm is of better precision than traditional CORDIC on average,higher speed than linear compensation.And it costs less resource than double rotations algorithm with pipeline structure.