With the increasing requirements on spatial resolution and actuator pitch, multilayer bimorph deformable mirrors are coming into wider application in adaptive optics. This paper discusses the coupling of actuators of multilayer bimorph deformable mirrors. A decoupling algorithm based on controlling gradients directly is presented. And a closed-loop adaptive optics system, which consists of a double-layer bimorph deformable mirror and a Shack-Hartmann wavefront sensor, is set up to validate this decoupling algorithm. Experimental results show that the intensity distribution at the image plane of the distorted wavefront is effectively improved when the modified closed-loop control is on. Besides, the experimental results fit well with the conclusion of numerical simulation.