Abstract: The major factors which affect the time averaging characteristics of integrating sound level meters, the effect of sampling frequency on the time averaging characteristics of integrating sound level meters which give LAeq by two-times average,are presented in this article. The verification of the analysis by experiments is also presented. The results show that the sampling frequency should be higher than 1000Hz in order that the time averaging charactelistics of this kind of integrating sound level meters could conform to relative standards and regulations.