Abstract: A BP neural network based algorithm for payload calculation was proposed. A high dimensional input-output system was formed to describe the non-linear relation between electrical parameters and payload. By the use of negative gradient of the network error feedback, network parameters were automatically adjusted, therefore the mapping connection between electrical parameters and payload can be solved. Experimental results and simulations show that the algorithm can solve the problem of the non-linear approximation, and achieve an error probability of e-3 with correlation coefficient up to 0.95.