An apparatus for a multifunctional outer cannula (1) for a colonoscope, which relates to an auxiliary device for colonoscopy and aims at solving the problems that a bent loop is prone to being formed in the feeding process of a soft endoscope, when water is injected into the enteric cavity, liquid is drained out of the anus and contaminates an examining table and clothes, and abdominal distension discomfort is caused to a patient when too much air is injected. The apparatus comprises a first steel wire (7), spirally arranged in the thick wall of an outer cannula (1), and a four-way pipe (4), arranged at the lower end of the outer cannula (1). The four-way pipe (4) and the outer cannula (1) are in close fit connection, an inclined face (1-5) is provided at the upper end of the outer cannula (1), and the oblique angle of the inclined face (1-5) is 30°-60°. A drainage hole (1-6) is formed on the side wall at the upper end of the outer cannula (1), the four-way pipe (4) is composed of a first axially-open hose (4-1), a first zipper (4-2), a first branch hose (4-3) and a second branch hose (4-4). The first zipper (4-2) is arranged at the axially-open end of the first axially-open hose (4-1), a closed pipe is formed by the first axially-open hose (4-1) by means of the first zipper (4-2), and the first branch hose (4-3) and the second branch hose (4-4) are arranged at the two sides of the closed pipe.Un appareil de canule externe multifonctionnelle (1) pour un coloscope concerne un dispositif auxiliaire pour coloscopie et vise à résoudre les problèmes suivants : une boucle courbée a tendance à se former dans le processus dalimentation dun endoscope souple, lorsque de leau est injectée dans la cavité entérique, du liquide est drainé hors de lanus et contamine une table dexamen et des vêtements, et un inconfort de distension abdominale est ressenti par un patient lorsque trop dair est injecté. Lappareil comprend un premier fil dacier (7), disposé en spirale dans la paroi épa
