The design of continuous autofocus algorithms often involves repetitive, time-consuming field tests on real scenes. This paper presents a simulation method to expedite the design by replacing laborious field tests with simulation tests. The modeling of scene dynamics is achieved by decomposing a dynamic scene into a sequence of static scenes and representing the sharpness responses of the video camera to each static scene by a reciprocal focus profile. Three different scenes and the associated dynamic models are incorporated into the simulation framework to obtain effective clues for the refinement of continuous autofocus algorithms. Experimental results are provided to show the effectiveness of this design-by-simulation method.