The inter-satellite baseline determination of a certain precision and data rate is a key factor for the realization of formation flying satellites technology.The optimal basis function approximation method was applied to process the measurement data with low sampling rate.The precision-keeping and high-rate interpolation technique for inter-satellite baseline determination was studied by means of measurement data processing.We focused on the analysis of the influences of the sampling rate and the random disturbance on the baseline parameter determination precision.Theoretical derivation illustrates that the precision of high-rate baseline parameters depends on the combined influences of the function approximation error and the measurement error.Simulations were performed based on the analysis of the variation characteristics of the inter-satellite baseline.The results show that the white noise level of the measurement produces more remarkable influence on the baseline determination than the function approximation error based on the currently available sampling rate.