The invention discloses a method for controlling microwave vehicle detecting radar, comprising the following steps: microwave detecting radar work parameter is evaluated; pulse compression in the range direction is carried out; sub-echo of each target vehicle is respectively extracted, and whether advancing vehicle exists is judged, speed search is carried out on data of each sub-echo of advancing vehicle, one matched filtering function is obtained after each search, pulse compression in the azimuth direction is carried out, and then the kurtosis value is calculated; if the largest kurtosis value is obtained, the search speed corresponding to the largest kurtosis value is the traveling speed of the vehicle, frequency modulation slope in the azimuth direction is calculated according to the speed and pulse compression in the azimuth direction is carried out, and then signals of each range gates are added and are compared with the set threshold to obtain vehicle length; if the largest kurtosis value is not obtained, then search is kept on by returning to the previous step. The invention has numerous monitoring lanes, wide detection range and more precise detecting speed, can detect vehicle with low speed or even standing vehicle precisely, and can estimate vehicle length, thereby facilitating traffic control.