The existing methods of leaf area measuring would cause certain damage to the leaf, so a measurement method of the leaf area in natural growing state was put forward. The digital camera was calibrated to get camera parameters; then leaf images at various angles in natural growing state were shot and processed by PhotoModeler software. The 3-D point cloud model of leaf was built up. The 3-D surface modeling and surface area calculating of leaf were achieved by using Matlab software. The measuring results and the calculating results with combination method of scanner and Photoshop software were compared. It showed that the accuracy of calculating results reached to 99%.