Abstract: Based on the Lband simulated fullpolarimetric data, forest height inversion by coherent DEM difference algorithm and amplitude coherent complex algorithms were conducted, and fullpolarimetric spaceborne microwave remote sensing data ALOS PALSAR has been verified by an instance. The results show: under simulated data, DEM difference algorithm seriously underestimated the forest height, the complex coherent amplitude estimation algorithm represented high accuracy. Due to temporal decorrelation and low registration accuracy, ALOS PALSAR data was difficult to estimate the forest tree height effectively.