The invention discloses a microalgae cell wall breaker. The breaker comprises a support frame, a sealing barrel arranged on the support frame and a stirring device arranged at the upper end of the sealing barrel, wherein a pressurization device for blowing air to realize pressurization in the sealing barrel is arranged at the lower end of the sealing barrel, a decompression valve and a vacuum pumping device are also arranged at the upper end of the sealing barrel to form a differential pressure wall breaking system for microalgae, an inner barrel structure rotationally connected with the sealing barrel is arranged in the sealing barrel, the inner barrel structure comprises an inner barrel body and an inner barrel blade arranged on the inner side wall of the inner barrel body, the rotationdirection of the inner barrel structure is opposite to that of the stirring device to form a stirring and cutting wall breaking system, a pressure detection device is further arranged at the upper endof the sealing barrel, and the pressure detection device, the stirring device, the inner barrel structure, the vacuum pumping device, the decompression valve and the pressurization device are in signal connection with a controller separately. The wall breaker can effectively improve the wall breaking effect and quality and improve the production efficiency.