Spherical multiprobe antenna nearfield measurement system has the advantages of fast test speed and being able to acquire the threedimensional nearfield data of the antenna to be tested. However, multiple probes form multiple channels, and different amplitude and phase characteristics of various channels will affect nearfield measurement accuracy. In order to eliminate the channel inconsistency, mechanical calibration of the multiprobe system is performed first, which reduces the angle and position errors of the probe. Then electrical calibration is performed through measuring the radiation signal from the center of sphere to each probe. Next, the influence of amplitude and phase errors caused by system errors and environment factors on the extrapolation of farfield radiation pattern from nearfield data is simulated and analyzed. A semispherical multiprobe antenna nearfield measurement system was built, and verification experiment was conducted. The results indicate the effectiveness of mechanical calibration and electrical calibration techniques. The calibrated nearfield data was extrapolated to obtain farfield radiation pattern, and the obtained radiation pattern was compared with the measured farfield radiation pattern. The comparison result verifies influence of amplitude and phase errors on extrapolated farfield radiation pattern.