The artificial neural network can dig out the regulation of the observed data fully to have a prediction to the unobserved data, and can be applied in the spatial interpolation of rainfall. Based on the traditional BP neural network in spatial interpolation of rainfall, this paper introduces the genetic algorithm, particle swarm optimization and ant colony algorithm to optimize the initial weights and thresholds of BP neural network, and are applied in the spatial interpolation of rainfall of year, month and day such three temporal scales in the Three Gorges region. The results showed that after the optimization of initial weights and thresholds of BP neural network by bionic algorithms, it can reduce risk of BP trapping in the partial smallest and the over fitting. There is a better stability in the interpolation process to get the ideal interpolation.