A signal converter is used to connect between an all-in-one USB connector and a PCB and has USB 3.0 and eSATA signal interfaces, an inner communication interface and a processing unit. The processing unit has an identifying and converting procedure. The identifying and converting procedure is periodically executed to detect the USB 3.0 and eSATA signal interfaces in sequence and determine whether a response signal is sent back from one of the USB 3.0 and eSATA signal interfaces. If a determined result is positive, the processing unit bi-directionally converts two different standard signals of the inner communication interface and the one of the USB 3.0 and eSATA signal interfaces that transmitted the response signal. Therefore, the PCB successfully communicates with the external electronic device through the correct port of the all-in-one USB connector.