In this paper, a large array high-resolution triple-zoom double telecentrica large front array high-resolution triplex double telecentric optical system is designed for surface defect detection of chips in the plastic encapsulation. Through the analysis of telecentric model and aberration optimization, a dual telecentric optical system with a large field of view, high precision, variable magnification and low distortion is obtained. The system uses a 6500 W pixel industrial camera consisting of 13 spherical lenses operating in the visible wavelength range with an F-number of 7, and magnification of -0.305^x,-0.427^x and -0.500^x, with an overall length of the system of less than 362mm. The design results show that the full-field-of-view modulation transfer function under different magnification is greater than 0.1 at the Nyquist frequency of 156 lp/mm, the maximum distortion is no more than 0.2%, and the telecycenter of the object is less than 0.2°. The optical system has good imaging quality, which has certain reference value of reference in the field of optical design for the detection of defects on the industrial surface.