In the big visual field photoelectric measuring system,distortion produced by optical system makes the image of objects on the linear CCD deviate from the theoretical point and lead to the system measuring error.In the practical measuring system,in order to improve measurement precision,distortion correction is necessary.According to optical theory of distortion and utilizing BP neural network to approach nonlinear distortion,distortion correction mathematic model of whole field was set up through training the distortion measurement data which were measured by distortion detection device.This device has eleven equidistance points of laser goals and is designed based on the basis of distortion mechanism and radical character.The distortion correction method based on BP neural network can realize high precision of correction without knowing the mathematic model.The experiment result shows that the device can reduce error obviously from -2.08 mm to -0.104 mm according to the BP neural network correction when the object height is 200.115 mm,and raise the whole systematic detection precision from 1.039% to 0.052%.