The utility model discloses a cone bottom structure of a furnace body. The dimension of S2, T2 and Y2 three-ring bricks of the fire facing surface maintains unchanged, the back space of the fire facing surface is built by adopting chrome corundum bricks, the cross section of a R2 ring brick at the upper part of the S2 ring brick is arranged into a ladder-shaped structure, in addition, the outer diameter of the R2 ring brick is unified with the outer diameter of the S2, T2 and Y2 three-ring bricks, and a P2 ring brick combined by P and Q ring bricks is arranged in the rest space of the cone bottom of the furnace body. The utility model also discloses a furnace body using the cone bottom structure. Chrome corundum casting materials at the back part of the fire facing surface are replaced by the chrome corundum bricks, so the effect of maintaining the back part structure unchanged when the fire facing surface brick of the cone bottom of a gasification furnace is replaced is realized, the great shortening of the cone bottom replacement time is realized, and the construction is convenient and fast.