Abstract: We present a method using multiple satellite clocks through the weight to determine the time base in autonomous orbit determination.On the basis of forecasting the clock errors of 32 GPS satellites in using the quadratic polynomials,Chebyshev polynomials,and the gray model,the good quality satellite clocks and forecast models are selected to establish the time base through certain weight.The experimental results show that using several satellite clocks to determine the time base will improve forecast accuracy and the results will be more stable,and the maximum residual is 42 ns when forecasting 180 days.