Based on the Acoustic Doppler Current Profiler (ADCP) data of buoy and mooring during Typhoon Kalmaegi (1415) in the northern South China Sea, a set of algorithms were proposed to calculate the spatial variation, data bias and correction. On buoys, the maximum horizontal displacement of ADCP can reach 2.61 km, the maximum horizontal velocity bias can reach 0.27 m/s, but the maximum vertical velocity bias is only 5×10-4 m/s after the typhoon. The velocity in thermocline of horizontal correction after typhoon is prominently larger than the observed velocity, indicating the horizontal correction is necessary for the quality control of the thermocline velocity. On moorings, the maximum displacement increments on the mooring are closed to 179 m, the maximum rope tilt angle can reach 35°, the maximum horizontal displacement of ADCP can reach 1.5 km. The horizontal velocity bias and tilt bias of ADCP are small to be ignored,the vertical correction can not be ignored for velocity of middle layer after typhoon.