The invention discloses a control method for an online detection system control cabinet and a control cabinet for an online detection system. The control cabinet comprises a machine table, wherein a detection platform is arranged on the machine table, the detection platform comprises a glass cover plate, a reference block for aligning a detected object is arranged on one side of the glass cover plate, and a linear motor is arranged on the other side of the glass cover plate; the linear motor is connected with a fixed claw for fixing the detected object, and the reference block and the fixed claw are arranged oppositely; a longitudinal guide rail is arranged on the machine table and is an air-float guide rail; a machine arm is arranged on the machine table and comprises a machine arm upright post, a transverse rail is movably connected to the machine arm upright post, and a transverse telescopic arm is movably connected to the transverse rail; the machine arm is connected with the central control unit through signals. According to the invention, products can be detected quickly, personnel errors are reduced, data are processed and analyzed quickly, labor cost is greatly saved, andeconomic benefits are improved.