In order to reduce the risk of severe deterioration in the Mogao Grottoes murals caused by unexpected environmental changes,the monitoring data from August 2011 to August 2012 were selected to analyze the regular patterns and differences of the micro-environments of caves under sudden rainfall vis-à-vis open caves and closed caves of similar size and shape situated on the same level of the cliff.The research results show that rainfall has little influence on the temperature inside the caves,but the relative humidity fluctuates obviously with a time-lag effect.Comparing the open caves with closed caves,the fluctuation frequency of relative humidity seems to be more obvious with the same lag time of 10 hours.It has to last for seven hours before reaching another relatively stable state.Therefore,the results provide evidence for a reasonable cave checking and visiting schedule.Meanwhile,this paper provides a theoretical basis for decision-makers to establish effective preventive measures in a timely manner.