The effect of hydrazine on blue membrane was investigated by the UV/VIS absorption spectrum technique and the flash photolysis technique, the results show that: hydrazine can convert blue membrane to purple membrane and the photocycle returns, but the rate of decay of photcycle intermediate(M₄₁₂) quickens, this phenomenon is not seen when metal cations are added to blue omembrane solution(the rate of decay of photcycle intermediate slowers). At the same time , the effect of pH and temperature on the interaction between hydrazine and blue membrane was investigated. When hydrazine was added to blue membrane solution, the sensitivity of the reaction is pH and temperature dependent. Over the pH range(2～4.8), the sensitivity of the reaction lowers with the increase of the acidity. Over the temperature range(20～40℃), the sensitivity of the reaction lowers with the increase of the temperature.