The utility model relates to a tapered sacculus expanding catheter used for percutaneous transluminal coronary angioplasty of interventional iatrotechnics. The tapered sacculus expanding catheter comprises sacculus, a catheter and a ruhr connector, wherein the sacculus is positioned at the front part of the catheter, the catheter is connected with the ruhr connector or connected with the ruhr connector through an armored tube, an inner tube is arranged in the catheter, the distal part and the proximal end of the sacculus respectively adopt a tapered section structure, and the middle section of the sacculus adopts a transitional taper structure; because the sacculus main body adopts the tapered structure, which conforms to the human engineering, to ensure the sacculus or the supporting frame which expands by depending on the sacculus to conform to the gradual thinner natural change of the inner diameter of human body from the near to the far, therefore, by adopting the sacculus, the damage to the blood vessel at the distal part because of over extension existed in the traditional sacculus can be reduced when the supporting frame is expanded, the wall contacting effect of the supporting frame is better, and the possibility of thrombus or narrowness repetition after operation is reduced; the penetration performance of the sacculus catheter penetrating the blood vessel or pathologic change can be enhanced by adopting the tapered structural design.