Valve clack structure of low-flow-loss butterfly valve

The utility model discloses a valve clack structure of a low-flow-loss butterfly valve. According to the low-flow-loss butterfly valve clack structure, the portions, provided with an upper shaft holeand a lower shaft hole, of the upper end and the lower end of a butterfly valve clack are of a stepped structure, and the portion, provided with the upper shaft hole, of the upper end of the butterflyvalve clack of the stepped structure is sequentially connected from top to bottom and integrally formed into a cylinder A, a circular truncated cone, a cylinder B and a ball table; the lower end of the butterfly valve clack of the stepped structure is provided with a lower shaft hole and comprises a cylinder A, a circular truncated cone body, a cylinder B and a ball table body which are sequentially connected from bottom to top and integrally formed. After the butterfly valve clack is fully opened, on the premise that the sealing performance is guaranteed, the ratio of the flow area to the drift diameter area of the b