Abstract: Holcocerus hippophaecolus exists in many areas and has become serious disaster in recent years.In order to expound and research this phenomenon and its mechanism further,six years' observation and research were carried out in the pest disaster regions of Ordos City,Inner Mongolia and Jianping County,Liaoning Province separately from year 2001.Investigation revealed that Hippophae rhamnoides growing in ditch,reservoir and flood land had strong power to resist the disaster.Six years of observation and research show that the factor influencing the resistance of H.rhamnoides to H.hippophaecolus is not the soil fertility but the soil moisture.Adequate water and fertilizer can enhance photosynthesis and the stocks of protein and other nutrients,also can reduce sugar and other simple compounds,C/N ratio decline,Na⁺/K⁺ ratio imbalance and the body temperature of tree drops.The results indicate that the resistance mechanism is the combined results of a series of antibiotic factors,which are induced by soil moisture.