The invention belongs to the technical field of concrete lining quality detection, particularly relates to a detection method of the canal lining quality in the south-to-north water diversion project. The detection method comprises the following steps: before detection, firstly learning the maximum concrete lining depth of a to-be-measured canal, then setting the antenna frequency, the time window and the dielectric constant of a ground penetrating radar according to the maximum depth; arranging a measuring line according to the concrete lining direction of the to-be-measured canal; performing overall continuous scanning on the concrete surface of the to-be-measured canal by using the ground penetrating radar according to the measuring line; analyzing the collected data through radar software, so as to precisely position the concrete thickness and the lower part detect of the canal. With the adoption of the detection method provided by the invention, the ground penetrating radar technology is adopted, therefore distinctive functions like high resolution, intelligence, non-destructiveness, speediness and continuous detection are achieved.