The principle of a polarization interference imaging spectrometer based on Wollaston prism is presented. The accurate optical path difference, splitting angle and fringe location plane of single Wollaston prism in four different conditions are calculated by wave-normal tracing method, and the theoretical formulas are introduced. The accurate values and approximate values of the optical path difference, the splitting angle, the fringe location are compared by computer simulation. The results show that the influences of wedge angle, incident angle and incident position on the accurate values and the approximate values are greatly different. The selection range of the wedges angle and the incident angle are deduced according to the accurate value, and the deviation of fringe location plane and its influence on Fourier transform lens are analysed. This study provides a theoretical and practical guidance for the study, design, modulation, experiment and engineering of the polarization interference imaging spectrometers.