Abstract: The present invention provides a Mitsubishi SEMI Equipment Communication (MSEC)/SEMI Equipment Communication Standard (SECS) protocol converter and conversion method thereof. The MSEC/SECS protocol converter and conversion method utilize an MSEC transceiver to transmit and receive MSEC signals, an SECS transceiver to transmit and receive SECS signals, an MSEC/SECS module to transform MSEC signals into SECS signals, an SECS/MSEC module to transform SECS signals into MSEC signals, and a control character transmission module to transmit control characters. With the MSEC/SECS protocol converter and conversion method, the computer host only needs the SECS interface to communicate the semiconductor apparatus with different protocols, which reduces the complexity and processing requirements of the computer host.