Abstract: To enhance the capacity of meteorological services for agriculture and reduce the loss caused by frost to agricultural production, we analyzed the characteristic of frost and the probability and the impact of disasters, which founded the data of frost and growth and crop yield from 1961 to 2015 at Wuwei counties (districts). Results showed that: (1) The first frost date was delayed 17-23 days at Wuwei counties (districts) in 55 years. The last frost date was advanced 20 to 29 days and the frost-free period was prolonged 39-48 days. The change coefficient of frost-free period > > last frost date> first frost date. (2) The last frost date was mostly positive anomaly in the 60 s to 90 s, the 21st century was most negative anomaly. The first frost date and frost-free period were mostly negative anomaly in the 60 s to 90 s, the 21st century was most positive anomaly. The anomaly amplitude was bigger in the 60 s to 70 s. (3) From the average ground lowest temperature when frost appeared, the probability of serious frost damage was 9% at Minqin, the Liangzhou was 2%. The probability of middle frost damage was 7% at Minqin, the Liangzhou was 7%, the Gulang was 2%. The probability of light frost damage was 84% at Minqin, the Liangzhou was 91%, the Gulang was 98%. (4) The influence of frost on thermophilic crops of spring corn was significantly greater than spring wheat. And the frost damage most sensitive period of spring corn was 3~ 7 leaves stage. When the first frost was earlier, the frost-free period was shorter, the spring wheat, spring corn and grain crops easily harmed by early frost and influenced yield. The last frost date was later, the spring wheat, spring corn and grain crops suffered from the late frost hazard risk was greatly increased.