99%。A navigation algorithm was studied, which as used to extract navigation route by machine vision based on agricultural non-structural characteristic. Firstly, a new algorithm was used to detect the ending region of farmland based on cluster's method. And then moving window was used to examine white pixels of the binary image to definite target regions. Finally, improved Hough transformation was used to extract navigation routes. The experiment proved that this algorithm can accurately extract the column information of green crops. The average time required for processing a 320×240 pixels color image was 57.404ms and the accuracy of the recognition reached 99%.