Method for detecting optimal sowing density of crop

The invention discloses a method for detecting optimal sowing density of crops. The method comprises the following steps of: firstly transmitting emission lines outward with a base point as the center in a test field; drawing up multiple circular rings or arcs outward, wherein cross position is a sowing base point; then calculating the sowing density in single circular ring or arc region according to ab/(Pi(nd+0.5d)2-Pi(nd-0.5d)2), wherein n is an nth circular ring or arc, a is the number of the sowing base points on the nth circular ring or arc, b is the number of seedlings reserved after sowing on each sowing base point, and d is the distance between adjacent sowing base points on the same emission line; and then carrying out statistic on crop yield on each circular ring or arc, and taking the highest unit area yield as the optimal sowing density. In the invention, crops are sown on multiple circular rings or arcs in concentric distribution, grading levels of cropping density are more, density gradient diff