The invention belongs to a visual measurement method for the volume of an irregular object. According to the method, firstly, a system is demarcated, and the pixel equivalent of the system is obtained; secondly, three cameras are utilized for respectively obtaining original images of an object to be measured in three directions of overlooking, left looking and right looking, and in addition, the maximal peripheral length image coordinate parameter of the object to be measured is obtained through a top view; then, a left view and a right view are subjected to three-dimensional reconstruction based on the gray level, and meanwhile, the maximal length pixel of the top view is used as the basis for cutting the reconstruction range corresponding to the left view and the right view; next, corresponding statistical algorithms are adopted for calculating the volume of a three-dimensional object in a three-dimensional model in an image coordinate; and finally, the practical volume of the object to be measured in a world coordinate system is calculated according to the pixel equivalent. The visual measurement method has the advantages that the image grey value is utilized for the three-dimensional reconstruction of the object in an image coordinate system, the volume of the object is calculated through the pixel value, only the pixel equivalent is demarcated in the method, the calculation speed is high, and the real-time requirement can be met in the precision range.