The JJ-7 is generall based on the J-7B fighter design, with the single-seat cockpit replaced by a tandem two-seat cockpit. The student pilot sits in the front seat and the trainer sits in the rear seat. The original single under-fuselage vertical stabilising fin of the J-7 is replaced by a two-fin design. As a result of the additional seat, the internal fuel tank capacity of the JJ-7 is smaller than that of the J-7B. An additional fuel tank is added on the back of the fuselage between the cockpit canopy and vertical tail. The single rear-hinged cockpit canopy of the J-7 is replaced by two side-hinged (open to right) canopies.