The effect of digital phase shifter with different digits on the course of antenna scanning and antenna calibration is analyzed in the paper. The antenna scanning accuracy and calibration error of digital phase shifter with four digits and five digits are also compared through simulation. The results show that the increase in the number of digits of digital phase shifter can obviously improve the scanning accuracy and decrease the calibration error. Because the increase in the number of digits of digital phase shifter needs to meet strict technique requirements and comes with high cost, the method should be considered reasonably in practical application.