Abstract: Through measure of image processing, we will make use of image pixel ratio and reference to test area of maize. Comparing with method of the correlation coefficient of analytic system on maize leaf area and method on leaf area equipment –CI202 were 0.9479, comparing with method of the correlation coefficient of analytic system on maize leaf area and and paper cutting were 0.9382,comparing with method of the correlation coefficient of analytic system on maize leaf area and method on leaf area equipment –LI-3100 were 0.8561. The result showed that it was suit for testing maize leaf area with analytic system of maize leaf area. To look for one counting method of testing maize leaf area, which was leaf length unlimited, handy, quickly, accuracy, no other power supply and used of outside. The beneficial supplement, rather than replace.