Effects of ambient temperature and injection pressure on evaporating process and droplet behavior of diesel spray was investigated by using a magnified nano-spark photography method and a rapid compression machine. Spray tip penetration becomes short with increasing ambient temperature. When ambient temperature rises up to 950K, penetration of liquid core becomes short. Magnified photographs reveal the detailed structure of evaporating spray. Droplets begin to evaporate near middle stream region of the spray. Some droplets fly while evaporating, and the droplets leave streamline at the back. The evaporation is promoted by injection pressure. Under the condition of high injection pressure, observed droplet size is small and the spray evaporation progresses strongly due to introducing high temperature ambient gas. Consequently, high-pressure injection produces wide gas phase region near the spray tip.