The invention provides a detection method of a cam contour detection device which has the advantages of simple structure and high detection accuracy and efficiency. The cam contour detection device which is adopted by the detection method provided by the invention comprises a digital control rotary table, a linear motor, a laser measuring head, a grating ruler displacement sensor, an encoder and an industrial personal computer, wherein the digital control rotary table is used for driving a cam to be horizontally and coaxially rotated around a vertical mandrel; the linear motor is horizontallyarranged at one side of the digital control rotary table; the laser measuring head is arranged on the rotor of the linear motor and at one side of the cam; the grating ruler displacement sensor is used for measuring the horizontal displacement of the rotor; the encoder is used for detecting the rotation angle of the cam; and the industrial personal computer controls the motion of the digital control rotary table and the linear motor and obtains the outer contour data of the cam according to the data which is obtained by the laser measuring head, the grating ruler displacement sensor and the encoder.