The invention discloses a distributed state feedback control method for the liquid level of a four-tank water tank. The method comprises that parameters of a distributed state feedback controller are initialized; a convex optimization problem composed of linear matrix inequalities is solved in an iteration manner, and optimal state feedback matrixes of sub-systems of a controlled object are solved; and the obtained optimal state feedback matrixes are applied to the corresponding sub-systems. Compared with centralized state feedback control, computing time of a controller is reduced under very low performance loss, and the safety, flexibility and reliability are higher; compared with dispersed state feedback control, the control quality is higher; and the distributed state feedback control method also has the advantages of high tracking speed, smooth tracking process, high anti-coupling performance and low stable-state error.