Disclosed is a displacement correction apparatus. The apparatus comprises: a reference circuit and a correction circuit; the reference circuit is configured to provide a reference signal; the correction circuit is configured to perform a logarithm operation on a nonlinear displacement signal to be corrected based on the reference signal, to obtain a corrected linear displacement signal. The displacement correction apparatus can solve the problem of poor detection accuracy resulting from a position signal output by an eddy current sensor being not in a linear relationship with a displacement signal of a shaft, thereby achieving the effect of improving detection accuracy. A magnetic levitation bearing system and a displacement correction method therefor which use the above displacement correction apparatus are also disclosed.