Abstract: In recent years, the area of acid deposition /acid rain (AR)in China is expanded increasingly. The study on monitoring technology on injury caused by AR is needed and stringent especially for the forecast and judgement of AR and the reduction of agricultural losses. According to the rese arches, the monitoring technology on injured plants by AR includes monitoring of visual injury and physiological injury. Monitored parameters involved in the latter are photosynthetic rate, stomatal resistance, cell membrane permeability, chlorophy ll content, cell pH value, stress reaction of activated oxygen defense system, etc. Measuring methods of injury, their advantages and shortages, the effect of AR monitor technology on agro-environmental monitoring and evaluation, agro-regional assignment environmental protection of acid deposition area are discu ssed briefly in the paper. Because the injury of crops caused by AR involves in physiology, bio-chemistry, zoology and so on, screening out the key index based on ecological and physiological researches on different crops under AR stress becomes the most important question. So it must be pointed out that the study, in the future, should emphasize on the improvement of the monitoring system and the expansion of the monitored objects.