The invention discloses a catheter comprising a main conduit, the catheter and a urine outlet, wherein the catheter is arranged on the side wall of the top end of the main conduit, and the urine outlet is arranged on the tail end of the main conduit; the top end of the main conduit is positioned on the lower part of a catheterization hole and is provided with an inner fixed air sac; the main conduct is provided with an air sac cavity; one end of the air sac cavity is connected with the inner fixed air sac, and the other end of the air sac cavity forms an independent air sac path port on the tail end of the catheter; the top end of the main conduit is provided with a conducting wire path for inserting a conducting wire; the periphery of the conducting path is provided with bulges which are connected with the side wall of the main conduit and are used for preventing a metal bougie from breaking the catheter; the bulges are positioned on the upper part of the catheterization hole and form a whole with the top end of the main conduit; and the bulge is provided with one or a plurality of grooves for preventing the metal bougie from slipping. The invention has simple structure, reasonable design, perfect function, convenient operation, safe and reliable use, low production cost, good using effect and convenient popularization and use.