The invention provides a cargo pallet detection method and system based on point cloud plane contour matching. The method includes the following steps: S1, original point cloud filtering; S2, point cloud plane segmentation; S3, generating a grid map through projection; S4, contour extraction; S5, contour matching; and S6, acquiring the relative position and posture. The system includes an original point cloud filtering module, a point cloud plane segmentation module, a module for generating a grid map through projection, a contour extraction module, a contour matching module, and a relative position and posture acquisition module. The method and the system are of low cost and high detection accuracy, and are basically not affected by illumination. There is no need for label laying or other operation, and there is no need to transform the storage environment. The method and the system are suitable for pallets of various colors and specifications, and have the advantages of high accuracy, low price, strong robustness, and the like.