With the global environmental change, extreme climate events occur frequently and meteorological disasters become more and more serious, and mountain disasters are frequent. Based on the long-term monitoring data from 32 meteorological stations in the Qinling Mountains, we conducted a study using the standardized precipitation evapotranspiration index (SPEI) as a quantitative indicator of drought and flooding. We haved studied the spatial and temporal characteristics, frequency, and periodicity of drought and flood in the Qinling Mountains over the past 60 years. The results showed that:(1) from 1960 to 2019, the annual SPEI index in the Qinling Mountains decreased at a rate of 0.124/10 a. Of which, 90.23% of the area showed a significant decreasing trend and 1.96% showed a significant increasing trend, and aridity mutation occurred in 1990. The aridity trend of the northern slopes of the Qinling Mountains was greater than that of the southern slopes, and the aridity was more obvious at high altitudes. (2) The average wetness ratio of the Qinling Mountains was 36.94% before the mutation, and decreased to 18.19% after the mutation. The aridity ratio increased sharply from 17.64% before the mutation to 38.19% after the mutation. The frequency of extreme drought events and severe drought events in the Qinling Mountains in the 30 years before the mutation was almost zero; the frequency of severe drought and extreme drought events increased in the 30 years after the mutation, and the extreme wetness and severe wetness events on the north and south slopes of the Qinling Mountains nearly disappeared. (3) On the whole, there is a negative correlation between sunspots and drought and flood changes in the Qinling Mountains. ENSO events had a greater impact on drought and flood changes in the Qinling Mountains, and were prone to flood events in La Nina years and drought events in El Niño years. The impact of SSTA (Sea surface temperature anomaly) on drought and flood changes in the Qinling Mountains is different in different time domains:before 1990, there was a significantly negative correlation between SPEI and SSTA; After 1990, there was a strongly cohesive resonance cycle of 5-6 a between SPEI and SSTA, and SPEI lags SSTA by about 1/4 cycle. These findings would be of important reference value for the prevention of droughts and floods on the southern and northern slopes of the Qinling Mountains, and the development of forestry and agriculture in the Qinling Mountains.