The invention discloses a support underframe capable of changing an inclination angle. The support underframe comprises two symmetrically arranged support frames, wherein the inner sides of the support frames are each connected with an angle adjusting device; each angle adjusting device comprises an angle adjusting plate and a locating block; a plurality of adjusting holes are formed in each angle adjusting plate; each locating block is connected to the corresponding angle adjusting plate through locating pins matched with the adjusting holes; a sliding bearing block is arranged at the top of each support frame; and a support shaft to be connected with a single-cylinder mixer or a double-cylinder mixer is arranged in each sliding bearing block. Change of a support angle can be achieved only by inserting the locating pins into different locating round holes through the locating blocks, and the support underframe is applied to the occasion of meeting inclined mixing at different angles.