Abstract: Scintillation optical fiber is applied to ray imaging more and more widely. In order to know more about some characters of scintillation optical fiber under ray radiation, the article analyses the relationships between good event rate of γray and fiber length and ray energy, and between energy deposition efficiency of γray and fiber length and ray energy by computer simulation based on Monte Carlo method. According to them, we can conclude some important results. For example, the scintillation fiber′s optimal length is about 10cm when applying it to imaging; its detecting efficiency is higher under low incident photons and lower under high incident photons. The work is very useful in the field of scintillation fiber imaging and dosage measurement.