This paper proposes a new stock-jobbing system named Stock-Master system which based on the SMS(Short Message System) of PSTN. For the real-time Stock Exchange, this system expands the system and the protocol of PSTN(Public Switched Telephone Network) SMS. It adds the trade module of CTSI(Chinese Terminal Service Interface) server, operation trade gateway and professional CP(Content Provider) system. This system adopts the terminal ID (Identification) identification, encrypted 3DES, and the exclusive connection serial number. All these techniques are used to ensure the security of the stock exchange. This paper describes the frame, the physical topology structure, the function and the security design of this system, and analyses its advantages and disadvantages in detailed.