Extreme climate elements such as torrential rain, extreme high temperature, extr emely low temperature and so on are always used to analyze and evaluate an extre me climate event. There was a continuous sleeting and freezing process with low temperature in the beginning of 2008. The process had the characteristics of l arge and sustained precipitation and snowfall, deep and longtime snow accumula tion, long time in daily lowtemperature with not so-low extreme low temperatur e. Therefore, it wasn't objective and accurate to choose any single one of these elements to analyze and evaluate this process. As a result, a comprehensive ind ex of sleet process was suggested，which takes largest number of days of rain and snow, total precip itation and snowfall as two indices to evaluate rain and snow, and takes largest number of days of continuous lowtemperature, average temperature and lowest t emperature as three indices to estimate low temperature. Meanwhile, in order to build a comprehensive index calculation model, these five indices were changed i nto dimensionless ones, and then summed with equal weight. The model was used to calculate the comprehensive index of the longest continuous sleeting and freezi ng process with lowtemperature of ten meteorological stations in Hubei provinc e. By comparing with the historical rank and recurrence period of the comprehens ive index, the process in 2008 was evaluated. The result showed that the model a nd method was objective, easy to be used and extended.