Abstract: The Bernese ECOM solar radiation pressure model is widely used in precise orbit determination (POD) for GNSS navigation satellites¹. But when used for BeiDou POD, the accuracy may not be the best when all the nine parameters are solved. The MGEX precise ephemerides of one year were collected. A one-year time series of the nine parameters were analyzed by orbit fitting. The results show that there are strong correlations between Bc/Bs parameters and Yc/Ys parameters. At the same time, the Bc/Bs parameters have a one year cycle and are an order of magnitude larger than Yc/Ys parameters. Sgnificance testing of the ECOM regression model results show that the significance level of Bc/Bs parameters is higher than Yc/Ys parameters. Experinments on orbit determination using different schemes with data from MGEX monitoring stations were carried out. The results show that only the five parameters that D0/Y0/B0/Bc/Bs yielded the highest precision of orbit determination, thus the five parameter EOCM model is better for BeiDou POD.