The invention discloses a computer-based convex polygon field unmanned aerial vehicle spraying operation route planning method. The method includes the steps: firstly, solving a linear equation of each edge of a polygon; secondly, finding out the longest edge of the polygon; thirdly, respectively solving the distance from each endpoint of a field boundary to the longest point, and finding out the point farthest from the longest edge; fourthly, selecting a group of equidistant parallel lines parallel to the longest edge between the longest edge and the farthest point; fifthly, solving two intersections of each parallel line and the field boundary and storing result sets into corresponding groups; sixthly, connecting the two intersections of each parallel line and the polygon into a line segment, and then cutting off the parts, located outside the field operation area, of the group of parallel lines so as to obtain a group of parallel line segments located in the field operation area; finally, planning out a route. The method is simple algorithm and good in universality, efficiency of unmanned helicopters for executing spraying operation to irregular fields can be improved, and energy consumption of flight is lowered.