In order to solve the tedious problems of traditional manual contact measurement with large workload,relatively difficult measurement conditions and affecting the normal living habits of cattle,a method for measuring cattle body size based on binocular depth estimation with target detection is proposed.Firstly,the images are collected by a binocular camera,and the object detection algorithm YOLOv5 (you only look once v5) is used to detect the feature parts of the body scale in the images,and combined with edge detection and other algorithms to obtain the cattle body scale measurement points.Secondly,the binocular stereo matching algorithm is used to transform the binocular two-dimensional images into a spatial three-dimensional depth information map,and the three-dimensional coordinates of the measurement points are read on the depth information map.Finally,the spatial Euclidean distance is used to calculate parameters of the cattle body scale in three-dimensional coordinate system.A test platform is built for the measurement,and the experimental results show that the measurement accuracy of the method is higher than the existing related methods,in which the average relative error of body length is 2.4%,the average relative error of body height is 5.9%,and the average relative error of the body oblique length is 3.3%,which provide a feasible demonstration for the measurement of cattle body scale.