Aimed at the error problems during practical engineering applications of wavefront detection based on phase diversity method when additional aberration is away from the focus mode, the impacts of these errors on the wavefront detection accuracy have carried on the quantitative analysis by taking the co- phasing of the segmented telescope are analyzed as an example, including focal plane position error, uncertainty of defocus amount, image alignment error, exposure delay and image noise. The method is presented to eliminate these impacts through modifying the phase diversity algorithm, the root mean square errors drop from 0.06λ,0.0581λ,0.0754λ,0.0796λ, 0.0737λ down to 5.8834 × 10^-4 λ,6.664 × 10^-4λ,3.5853 × 10^-5 λ,6.1837 × 10^-5 λ,0.0013λ respectively after correction, and the wavefront detection accuracies are still maintained in the same order of magnitudes as above even when errors are in a quite large range. The results show that the proposed method can effectively eliminate the errors, vastly improve the wavefront detection accuracy and has guiding significance for the usage of phase diversity wavefront detection technology in practical engineering.