Scraper conveyor was an important equipment for fully mechanized coal mining work. It was equipped with a connecting pad between head frame and transmission device of scraper conveyor. In order to facilitate the installation, observation and maintenance of the coupler in the connecting pad, there was a need for a viewing hole on the coupling frame, and a larger viewing hole improved the convenience of overhaul and maintenance of the equipment in the frame, but oversize observation hole would affect overall strength of the connecting pad. Based on that situation, connecting pad of SGZ800/800 scraper conveyor was taken as an example, the finite element analysis method was used to parameterize the observation hole of the frame. The influence of the length and width of the observation hole on the ultimate deformation and stress of the frame were analyzed, which peovided reference for size choice and optimization of observation hole in connecting pad.