Abstract: This paper introduces three Baidu decryption methods including equivalent offset coordinate method,grid method and BP neural network.In addition,the general difference formula is obtained based on equivalent offset method.The cities of Urumqi,Lhasa,Lanzhou,Beijing,Shanghai and Sansha are selected to build the 0.1 degree square research area with each city center.The predicted WGS-84 coordinates translated by those methods are compared with the references to analysis the difference of the latitude and longitude and the positional error distribution.And the experimental results show that the coordinate decryption accuracy are about 10 m,20 m,50 m,and 100 m respectively.Simultaneously,it also researches the differences of calculating distance and area by Baidu online tools and the first-order and two-order equivalent offset difference method respectively.

Key words: Baidu coordinate, general formula of equal offset, BP neural network, grid method, accuracy evaluation