Principal component analysis (PCA) spike sorting hardware in an integrated neural recording system is highly desired for wireless neuroprosthetic devices. However, a large memory is required to store thousands of spike events during the PCA training procedure, which impedes the on-chip implementation for the PCA training engine. In this paper, a mean pre-estimation method is proposed to save 99.01% memory requirement by breaking the algorithm dependency. According to the simulation result, 100 dB signal-to-error power ratio can be preserved for the resulting principal components. According to the implementation result, 6.07 mm² silicon area is required after a 283.16 mm² area saving for the proposed PCA training hardware.