In computer graphics, according as the rapid development of hardware can realize high-resolution image on the monitor, the more natural and accurate rendering skill is needed gradually, and the studies about high-level rendering algorithm are processing. There are two types in rendering skill. The one is photo-realistic rendering to realize accurate image like photos and the other is real-time rendering to realize rapid real-time render. This paper includes caustics expression about lights and materials of several photo-realistic rendering skills. First this paper analyzes how caustics is used and expressed in movies, and further realizes caustics effect using real renderer. This paper examines objective criterion and capability of plug-in through the objective experiment of renderer. Also this paper analyzes using environment on variables for caustics effect realization. The experimental results can be applied to many rendering works as useful data, and can be used as data to understand characteristic and capability