Abstract: Because the essence of the traditional X-ray pulsar navigation (XNAV) is to measure and convert the time accurately, the errors of time measurement and conversion can affect the navigation precision. In the paper, measurement difference is adopted to reduce the effect of time measurement and conversion errors to navigation precision. Results demonstrate that double differences can reduce the effect of time measurement error to navigation precision, but can not reduce the effect of time conversion error to navigation precision, meanwhile, triple differences can reduce both the effect of time measurement and conversion errors to navigation precision. The research results are referable to the application of XNAV.