Abstract: Considering different canopy structures for the whole crop growth stages, it is not suitable to use traditional instrument to measure crop LAI for some growth stages, such as crop early growth stages with very sparse canopy structure. In order to obtain comparable and coherent LAI, the authors proposed the new method for corn LAI measurement, namely improved harvesting method (IHM). The IHM can reduce the measurement workload and the corn damage. Through the single corn total area comparison based on the two computing methods, namely the regression method and the shape factor method, it is shown that the regression method is better than shape factor method. Furthermore, based on the analysis of the ratio of stalk area to total area for the whole growth stages, the authors draw the conclusion that the stalk area must be considered for accurate LAI measurement. This work can provide some references for similar research and can accumulate the priori knowledge. The research of this paper will improve the study of LAI inversion and validation for remote sensing data.