This article is based on the objective requirements and main technical difficulties of natural icing flight test for developing of civil aircraft. It deeply studies the background and limitations of the formation of icing meteorological standards in Ap-pendix C of CCAR25, and proposes a flight method for ice detection using icing test research aircraft. This method includes the selection, modification, detection target area determination, flight operation strategy, flight safety management, data pro-cessing, etc. of experimental research aircraft. Based on statistical analysis of detection data, the selection criteria for meteor-ological conditions for natural icing flight test of civil aircraft have been determined. The compliance processing methods and criteria for a series of meteorological data, such as cloud gaps, liquid water content, total water collection rate, icing rate, icing thickness, and degree of ice shedding, have been standardized. The domestic icing meteorological prediction algorithms have been calibrated and verified, and the safety control strategies and risk degradation measures for natural icing flight test have been explored, providing strong support for the qualified certification of civil aircraft flight test.