Aircraft icing is an important and dangerous weather condition that affects flight safety. Accurate diagnosis of aircraft icing is of great significance to the operation and safety of civil aviation, especially with the advancement of airworthiness certification of domestic large aircraft; the diagnosis of aircraft icing potential attracts the attention of many departments such as civil aviation and meteorology. In this paper, referring to the improved CIP (Current Icing Potential) index, the fuzzy logic method is used to increase the correlation between the vertical velocity and the liquid water content in the cloud affecting aircraft icing, and optimize the aircraft icing potential equation to obtain the SCIP (Simplified Current Icing Potential) index. The index gives a relatively accurate aircraft icing potential directly based on atmospheric layer data and has the characteristics of a high hit rate and strong practicability in the diagnosis of aircraft icing. The aircraft icing potential diagnostic indexes are compared and validated, using the China Civil Aviation Aircraft reports from 28 February 2021 to 31 December 2021. The icing potential index is applied to reanalysis data to simulate historical icing events. Compared with the improved CIP index, the SCIP index shows better Receiver Operating Characteristic Curve (ROC) and True Skill Score (TSS). The results also show that increasing vertical velocity and cloud liquid water content in the aircraft ice accumulation potential diagnosis algorithm are crucial to avoid the warning of air alarms. However, for different degrees of ice accumulation, the improved CIP index and SCIP index show a consistent diagnostic effect, indicating that the SCIP index plays an important role in the diagnosis of aircraft ice accumulation potential but cannot judge the ice accumulation intensity. In order to further evaluate the influence of increasing vertical velocity and cloud liquid water content in the aircraft ice accumulation potential index, reanalysis data are used to calculate the aircraft ice accumulation potential of an individual case of aircraft ice formation in Shaanxi Province on 16 March 2020, indicating that increased upward vertical velocity and larger cloud liquid water content provide better conditions for aircraft ice accumulation under the condition of low cloud top temperature. The SCIP index makes up for the shortcomings of the improved CIP algorithm in the diagnosis of aircraft ice accumulation potential under this weather condition, indicating that the increase of these two factors is of great significance to improve the diagnosis effect of ice accumulation potential.