An acid liquid mixing device used for acidification for yield increasing is disclosed. The device includes a liquid mixing tank the top of which is evenly provided with a plurality of feeding pipes, with a stirrer being disposed in the liquid mixing tank. The device also includes a buffer storage tank right below the liquid mixing tank, and an acid injecting tank right below the buffer storage tank. The buffer storage tank communicates with the liquid mixing tank and the acid injecting tank respectively through a pipe having a vertical axis. The pipes are provided with valves. A plurality of pH testers evenly distributed along the vertical direction are disposed in the buffer storage tank. A display screen is fixed to the external surface of the buffer storage tank. The inside of the acidinjection tank communicates with a perfusion pump. The pipe between the buffer storage tank and the acid injecting tank is also provided with a turbulent flow device including a plurality of arc-shaped plates fixed to the inner wall of the pipe. The arc-shaped plates are distributed in the pipe along a spiral line. The device overcomes a problem that acidification processes in the prior art require a high number of containers having large volumes, and achieves objectives of increasing the acidification efficiency and reducing the engineering cost.