This paper aimed to estimate the crown volume by precise 3D laser scan system. Experiment was carried out to scan 13 different trees to get crown points. In the processing 3D laser scan data, crown volume modeling by multi-face would be greater then the actual volume and it would be hard to in modeling depression surface of crown volume points. The paper proposed a method to model crown volume by perspective density, which was more scientific and accurate than the way to simulate the crown like truncated cone. Introducing perspective density to estimate the crown volume made the method much easier. Through scanned crown volume of some coniferous and broadleaf trees, crown volume of coniferous was less than the broad-leaved crown when they get approximate shape.