A locking composition of a cascade module comprises a slide lock hook (1), a lock piece (2) and guide tracks (3); the guide tracks (3) are respectively arranged on housing surfaces of two adjacent modules; two ends of the guide track (3) are respectively provided with a recessed point B and a recessed point C; the slide lock hook (1) is designed as a half surrounding shape structure and clamped on the housing. Two recessed points B and C of the guide track (3) is matched with a protruding point A of the slide lock hook (1), thereby providing opening and locking positions for work personnel.