ICCD is one of the opto-electronic image sensors, commonly used in neutron low-light-level imaging system and the coupling of CCD and Image-Intensifier is the key technology in ICCD. This paper discussed the structure of ICCD, and simulated the coupling of relay lens, cone fibers and grin lens based on ZEMAX. We analyzed and checked their parameters such as geometric image, MTF, coupling efficiency, etc. Experimental results show that: The coupling of relay lens has high image quality; the coupling of cone fibers has high coupling efficiency; the performance of grin lens falls in between.