Recently, the testing process of the crimping quality of the existing tensioning clamps of transmission lines is complicated, which lacks of effective and convenient testing method. Therefore, in order to eliminate the regulatory blind spot in the production of new aluminum alloy core aluminum wires in the field of crimping of metal fittings, an ultrasonic testing method for the quality of crimping quality of aluminum alloy core aluminum wires based on the pulse reflection method is proposed in this paper. Though ultrasonic testing and tensile testing subjected to tensile clamps for the different length of the gap between the wire and the steel anchor, the reflection characteristics of the pulse in the crimped wire and the non-crimped wire was studied, and an ultrasonic field testing scheme is given. The research results showed that the ultrasonic detection technology based on the pulse reflection method has been certain validity and accuracy for the detection of the wire crimp quality and the measurement of the wire crimp depth. What’s more, the breakage hidden dangers caused by the unqualified quality of the tension clamp can be timely detected, to improve the operational reliability of transmission lines.