Abstract: A nailing unit and a nail gun including the nailing unit includes a guide plate, a nail box to mount staple nails or straight nails, and a nail feeding plate slidably connected to a nail compartment; the nail box is fixedly connected to a guide plate at one end, and forms a nail outlet at the position of connection; the nail feeding plate can push staple nails or straight nails to the nail outlet; bumps are fixedly provided inboard of the guide plate lengthwise; two bumps and the nail outlet form a nail discharge groove for matching the nailing plate, and suit to different specifications of straight nails or staple nails.