The invention relates to a non-contact measuring method for a leaf apex radial clearance of an engine rotor, and the method comprises the following steps: 1) assembling a measuring system, calibrating a sensor and determining the relation between the radial clearance and voltage of a leaf apex; 2) preparing before measuring; and 3) measuring the leaf apex radial clearance of the engine rotor. In the measuring method provided by the invention, a measurement technique based on a capacitance method is adopted; the measuring course and the assembling are synchronously carried out; the once cartridge disassembly and assembly is reduced; the measuring time is shortened; the production efficiency is improved; and the measuring accuracy is improved, thereby improving the assembly quality of an engine and reducing the failure rate of the engine. The non-contact measuring method provided by the invention is mainly used for measuring the leaf apex radial clearance of the rotors of parts such as an engine, a high-pressure compressor, a low-pressure compressor, a high-pressure turbine, a low-pressure turbine and the like.