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 -0.305x,-0.427x and -0.500x,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.