A circuit structure and a fabrication method thereof are provided. The fabrication method of the circuit structure includes the following steps: providing a substrate; fabricating a test circuit component on the substrate; fabricating a solder pad on the test circuit component; fabricating an insulating layer; and fabricating a conductive pad on the insulating layer. A second surface of the insulating layer covers the test circuit component and the solder pad. The conductive pad is coupled to the solder pad. Through the fabrication method of the circuit structure provided by the disclosure, circuit quality of the circuit structure may be monitored, and that reliability of the circuit structure provided by the disclosure is improved.