In order to improve real-time focusing in the bionic vision system,an improved fast focusing method based on liquid zoom lens is proposed,which achieves fast adjustment of focal length. Firstly,the active focusing result based on laser displacement sensor is taken as pre-focal judgment criterion. Then the focal length of the system is finely adjusted through the gray gradient evaluation function based on Sobel operator and the improved climbing search algorithm. An experimental device of the bionic vision imaging system was built,and the accuracy and real-time of this focusing control method were verified. Results show that the processing time of this method for 24 images with different fuzzy scales under the same scene consumes only 257 ms in the process of focus adjustment,and this method has greatly improved the focusing speed compared with the traditional automatic focusing method.