The present invention provides a warning envelope generating method for a civil aircraft terrain awareness and warning system. The method comprises: a step S1 of, according to the initial fight state of an aircraft, building a normal flight path model of no warning conditions, generating a no-warning normal flight path, meanwhile building a pilot evasive operation model, generating an evasive path of the aircraft after warning, comparing the two flight paths with first-order Markov random terrain data separately, and determining whether the warning in the flight simulation is successful; a step S2 of carrying out massive flight simulation, performing statistics on the false warning rate and the warning success rate as warning performance indexes of the system, creating an SOC curve, weighing the influence of the two indexes on the system, and selecting an optimum warning threshold point; and a step S3 of generating the whole warning envelope. According to the invention, the influences of false warnings and missed warnings on the warning system are taken into consideration, so that the warning envelope finally generated is reasonable, and the occurrence of false warnings and missed warnings is reduced.