The bending of the basic shaft inside the natural rubber latex-made balloon catheter caused the stretching deformation of the basic shaft which is resulted from the introduction of nominal capacity of air or sterile water into the balloon using charging funnel was investigated. The experimental results showed that

the control of the basic shaft diameter of the catheter to a rational value

the control of the single-layer thickness of balloon film from 0. 50 to 0. 65mm

the using of low-modulus prevulcanization formula

and the using of prevulcanized blend of natural rubber latex concentrate and 20 phr of MG 49 latex as the basic shaft compound or incorporation of 30 phr of calcium carbonate into the compound for the basic shaft to increased to hardness of the shaft are effective methods to reduce the bending of the basic shaft of natural rubber latex-made balloon catheter.