Noise transfer characteristic is a typical clock synchronization characteristic of network element in transport network. Traditional frequency selection method is inefficient

and it is difficult to display the in band gain of the device fully. Through the analysis of the relationship between Time Deviation（TDEV） and noise transfer frequency response

an improved noise estimation method based on TDEV is proposed in this paper. The experimental results show that the proposed method effectively solves the shortcomings of the existing frequency selection method for the aspect of testing efficiency or accuracy. It is believed that the proposed method can meet the test requirements of the traditional carrier network equipment clock and the enhanced synchronous ethernet equipment clock noise transfer characteristics for 5 G ultra-high precision.