Objective: For solar magnetic field telescope with birefringent filter

the quality of filter directly affects the transmission band

and then the measurement of solar magnetic field. The transmission band will shift and its outline will change when the incident ray is oblique or the optical elements are not ideal. The quality of filter can be improved by reducing the errors effectively after analyzing the effects of error terms on the birefringent filter. Method: Based on the ray tracing method

the trace of the ray can be simulated completely by using computer program. Ultimately the variation of transmission band with different errors can be obtained accurately. Result: The primary error terms were given which cause the band shift

the band broadening

and the changes of maximum and minimum. This paper provides a reference on the development of birefringent filter.