The integrated wide-area differential system of BDS broadcasts differential corrections to compensate broadcast ephemeris errors and enhance user positioning accuracy. It uses real-time pseudo-range observations from ground monitoring stations and calculates differential corrections, which are then broadcasted to users through the GEO satellites. Previous studies show that apparent code biases exist for BDS tracking stations, which in turn will affect the accuracy of differential corrections. This paper analyses the long-term pseudo-range biases based on the residuals in the Precise Orbit Determination (POD), the characteristics of the mean and standard deviation of the pseudo-range bias are studied. A code bias correction model is proposed and applied to BDS wide-area differential calculation. Performance of the code bias model is analysed in real-time pseudo-range based positioning. Results show that: UDRE and user positioning accuracy are improved, where the satellite UDRE is reduced from 0.43 to 0.35 m, and the user positioning accuracy is increased by 10.6% and 14.6% in horizontal and height directions, respectively.