Through theoretical analysis and numerical simulation of many phasestepping algorithms, it is concluded that the detector nonlinearity would introduce systematic error with twice spatial frequencies of the interference pattern into the result phase. Relative error of nonstandard phasestepping algorithm will increase as the detector nonlinearity increases. An error compensating technique that the phase shift error of PZT and the nonlinear error of the optoelectronic detector counteract with each other is reported, and the practical errormatching criterion is presented. The simulation shows that this technique reduces the measurement error with near one order of magnitude. It is proved that the standard phasestepping algorithms have perfect zero error response to nonlinear detectors and no effect on the accuracy of the device exists, when the amplitude information of the wavefront is ignored.