The invention relates to a forest single-tree height estimation method combined with LiDAR point cloud and a synchronous remote sensing image. The method comprises a step of obtaining forest area lowdensity airborne LiDAR point cloud data and a synchronous high-resolution aerial remote sensing image, a step of obtaining a target area digital orthophoto map (DOM) through carrying out inlaying andortho-rectification on a target area synchronous aerial remote sensing image, a step of obtaining a single-tree canopy position, canopy boundary information and single-tree crown width information from the digital orthophoto map, a step of processing the airborne LiDAR point cloud data of a research area and obtaining point cloud data in corresponding single-tree canopy with the combination of obtained single-tree canopy information, a step of constructing a three-dimensional tree height model based on an above result, and a step of optimizing and reconstructing a three-dimensional tree modelin three conditions that a number of laser points within a single-tree canopy is larger than 1, is equal to 1 and is zero, and thus calculating and obtaining a height value Ztop corresponding to a canopy vertex. A tree height estimation level is improved to a single-tree level, and the precision of estimating a stand single-tree height is effectively improved.