The invention belongs to the technical field of radar target detection, and discloses a radar multi-target detection method based on trapezoid LFMCW (linear frequency modulation continuous wave) modulation. The method includes the steps: transmitting a trapezoid LFMCW signal by a radar target, and receiving a target echo signal to generate digital differential signal; calculating an upper frequency band scanning spectrum peak, a constant-frequency spectrum peak and a lower frequency band scanning spectrum peak, combining pairwise the upper frequency band scanning spectrum peak and the lower frequency band scanning spectrum peak to obtain two spectrum peak combinations, calculating corresponding frequency and magnitude differences, and performing arrangement according to an ascending sequence of the magnitude differences to obtain a sequence S; marking a three-spectrum peak combination meeting a first frequency matching condition according to a frequency priority principle; marking a three-spectrum peak combination meeting a second frequency matching condition according to a frequency priority principle if an unsuccessfully-matched constant-frequency spectrum peak exists; marking L-P pairs of three-spectrum peak combinations meeting the second frequency matching conditions according to an amplitude information priority principle if P is not equal to L; calculating a target distance estimation value and speed estimation value. According to the method, a false target can be decreased, and detection reliability is improved.