The invention provides a uniprocessing system based on a hardware data transformation technology and a network security isolation method thereof, wherein the system and method have advantages of high security and reliability, simple structure, convenient maintenance, and high efficiency. According to the invention, the system is deployed at a network boundary that needs to protect an inner network from being attached by an outer network and prevent leakage of data of the inner network to the outer network; and unidirectional information inputting from a low-security zone of the outer network to a high-security zone of the inner network in fields including but not limited to government and defense fields as well as unidirectional information transmission from a high-security zone of the inner network to a low-security zone of the outer network in the industrial control field can be realized. On the basis of combination of the uniprocessing system with the hardware network protocol unloading structure, a TCP/UDP application layer data flow at a network input/output terminal is monitored and the application data flow direction and the return data channel width are limited. Therefore, the structure becomes simple, the maintenance becomes convenient, and the operation becomes reliable, and the efficiency is substantially improved; and the system and the method are suitable for the uniprocessing security isolation network boundary with the high bandwidth flow requirement.