In order to improve the accuracy of radar system parameter estimation, this paper proposes a data fusion and probabilistic fusion method for parameter estimation based on Bayesian principle. We derive the distance information, entropy error and mean square error for a multi-radar system under additive complex Gaussian noise conditions, and derive an upper bound on the distance information . The theoretical derivation shows that the maximum a posteriori estimate of the position estimation is consistent with the maximum ratio of the position information and that the equivalent signal-to-noise ratio of the multi-radar system is equal to the sum of the signal-to-noise ratios of the radars in the system.