The embodiment of the invention provides a computing method based on a neural network. The computing method comprises the steps that an original image of the tensor form is acquired; fixed point computation is performed on the original image of the tensor form; an image thermal diagram is generated based on the output data of fixed point computation; and the original image is marked based on the image thermal diagram. According to the computing method based on the neural network through the fixed point method, fixed point computation is adopted so that computing burden is low, resource occupation is less and thus the requirement for hardware is low.