In this paper,we present an auto-focusing and ranging method which is based on light-field imaging spatial refocusing principles and simulation algorithm.The clearest image could be chosen among the refocused image sequences by using image-resolution evaluation functions when we select the window of the object whose distance needs to be measured.Finally,we measure an object on the scene with the auto-focusing and ranging method and analyze its range and accuracy.The experimental results show that the aotu-focusing and ranging method could obtain distance information of different objects using one shooting light-field image and then measure the distance of two or more objects in one scene.