When checking a third fighter aircraft which is in service with the standard of 1797, it is thought that it is more reasonable to get time domain indices such as ratio of peak values uprising time etc. with time response curve obtaining through transferring function of high order system. A method to determine neal - smith criteria with optimization technique is put forward in this paper and the method works very well. By comparing the results calculated out with the actual flying qualities of an aircraft, it shows that some of criteria in 1797 on the short period flying quality of an aircraft are too strict to be met, so when they are applied to evaluating the flying qualities of an aircraft, a reasonable adjustment should be done according to the actual application and some guidelines should be given in detail, in this way, some un-compatible results can be explained very well.