An improved method of tonality determination based on order analysis i s suggested to solve the frequency aliasing problem appeared in practical applic ation of the method based on narrowband analysis and psychoacoustics in IEC6140011 standards. In the improved method, the analysis methods of nonstationary signal s，especially the vibration feature analysis methods of rotating machinery, are i ntroduced into the tonality determination procedure. The comparative analysis of field measured noise signals shows that the improved method can effectively sol ve the frequency aliasing phenomenon existing in the old method. The results show that the method is of a certain value to engineering application.