The hardware facilities and technical methods related to non-contact measurement of pig body size have undergone significant changes with the advancement of technology in fields including visual sensors and computer vision.Visual perception needs to meet three-dimensional requirements，and corresponding equipment have been updated from black and white cameras to depth equipment.The types of equipment usually determine the basic implementation plan and technical methods，however，current studies in this field mostly focus on specific algorithm details，which is difficult to meet the requirements of practical engineering.This article focused on the types of visual sensors and outlined different engineering deployment solutions for non-contact measurement of pig body size.The methods of equipment use and the environment and methods of data collection were summarized.The five tasks of 3D point cloud technology in measuring pig body size were analyzed.The advantages，disadvantages and potential for improvement of current studies and solutions for combination with applications of practical engineering were reviewed.The difficulties in studies on combining deep learning with 3D point cloud technology were prospected.The results of comparison showed that depth equipment and 3D point cloud technology are the directions for future applications of engineering in this field.Deep learning-based point cloud segmentation，point cloud completion，key point detection and other technologies have good prospects of application.It will provide a reference for the subsequent studies on non-contact measurement of pig body size.