The invention discloses a structured text (ST) code processing method. The method includes that a structured text code is converted into a C code according to a program organization unit, predefined interface function is embedded in the C code, the C code is compiled into a binary component capable of being loaded and replaced independently by calling a compiler, the singular program organization unit can be replaced independently under the running state of the device, and efficient running and reliable incremental updating of applications of IEC61131-3 standard structured text code are ensured. The invention further discloses a structured text code processing system which comprises a structured text editing module, a code conversion module, a code compiling module, a communication module and a system software module.