Based on the aircraft icing data of Yunnan Province from 2017 to 2022, the spatial and temporal distribution characteristics of aircraft icing along major flight routes and the applicability of different aircraft icing forecasting algorithms in Yunnan airspace were analyzed. The results show that: (1) Aircraft icing along major air routes in Yunnan mainly occurred from December to February and April of the following year, with fewer events in summer and the most in winter. (2) Aircraft icing events occurred at the altitude from 3300 to 9500 m. The aircraft icing events occurred most frequently at the altitude between 7000 and 8000 m, and severe icing events were also most frequent within this altitude range. (3) Aircraft icing mainly occurred within the temperature range of −15~−5℃, relative humidity of 90%~100%, vertical velocity of −0.05~0.05 m/s and cloud liquid water content of 0~0.05 g/kg. (4) The Simplified Forecast Icing Potential (SFIP), developed based on the fuzzy logic forecast diagnosis method, performed better than the classical icing index (IC) recommended by the International Civil Aviation Organization (ICAO) in terms of forecasting accuracy, intensity prediction accuracy, and missed detection rate for aircraft icing along major routes in Yunnan. (5) After weight optimization, the improved SFIP index (ISFIP) further enhanced the accuracy of aircraft icing forecast and intensity forecast on the main routes in Yunnan, while reducing the missed detection rate.