The invention relates to a design method of an air inlet channel lip of a hypersonic flight vehicle, and belongs to the technical field of hypersonic air inlet channel application. According to the design method, an air inlet channel is arranged on an engine of the flight vehicle, and the front end of the air inlet channel is a sawtooth-shaped lip; and the sawtooth-shaped lip comprises a pluralityof lip blades, the side walls of the lip blades are connected in an end-to-end mode to form the closed sawtooth-shaped lip, the center of the sawtooth-shaped lip is taken as a revolving axis line, and the lip blades are arranged in an array mode by taking the revolving axis as an array axis. According to the design method of the air inlet channel lip of the hypersonic flight vehicle, a moving mechanism is not introduced, so that the weight and the complexity of the system are prevented from being increased, and the problems of connection, sealing, cooling, control and the like are prevented from occurring; the machining and manufacturing process is simple, the starting performance of the axisymmetric air inlet channel can be improved, meanwhile, the compression performance of the axisymmetric air inlet channel is not influenced, and the capture flow is reduced, so that the working efficiency of the air inlet channel is guaranteed, and the starting performance of the air inlet channelis improved.