Abstract: Reflecting the direction and velocity of the movement, ascent and descent rate are important parameters in the migration of the insect. Traditional entomological radars have some problems such as low range resolution and primary target detection and association algorithm, which make it difficult to extract the ascent and descent rate. In this paper, we proposed an ascent and descent rate extraction algorithm based on Radon transform. The pulse Doppler and cell-averaging constant false alarm rate were employed to transform the two-dimensional data matrix from a series of M radar echoes to the binary image indicating the traces of insects. As for the binary image, Radon transform is utilized to extract the ascent and descent rate. Experimental data were processed to verify the validity of the proposed algorithm.