The invention relates to the technical field of chemical agent storage, in particular to a defoaming agent storage tank with an external stirring mechanism. The defoaming agent storage tank with the external stirring mechanism comprises a main tank body. An inner tank body is arranged in the main tank body. Multiple longitudinally arranged control strips protruding outwards are fixedly connected to the outer side face of the main tank body, and longitudinally arranged control grooves are formed in the outer side faces of the longitudinally arranged control strips. Rotating bases are movably connected to the inner bottom faces of the longitudinally arranged control grooves. Rotating rocker bars are hinged to the upper ends of the rotating bases. According to the defoaming agent storage tankwith the external stirring mechanism, the rotating rocker bars are arranged in the longitudinally arranged control grooves in the outer side wall, the rotating rocker bars control inner rotating gears to drive the inner tank body to rotate, and therefore the function of stirring in the inner tank body is achieved; and in this way, the functionality is greatly improved.