The invention discloses a circuit system security protection chip. The chip comprises interface input and output logic, a dual-port RAM, internal data input and output logic, an encryption algorithm module, an interface control module, an internal register bank, a voltage detection module, a frequency detection module, a chip tamper-proofing module, a bus encryption module and a hardware 3DES algorithm coprocessor, wherein the control module is in bidirectional connection with the internal data input and output logic, the encryption algorithm module, the internal register bank and a DMA controller, and signals flow in two directions; the signal input end of the control module is connected with the signal output end of the interface input and output logic; the voltage detection module is used for resisting attacks by high and low voltages; the frequency detection module is used for resisting attacks by high and low frequencies; the chip tamper-proofing module is used for designing a unique serial number of the chip; the bus encryption module is provided with a metallic shield protective layer and used for self-destruction of internal data after external attacks are detected. Operation of the encryption chip and input of external data can be basically performed at the same time, and high speed of data flow read-write in a DMA burst read-write mode can be fully utilized to increase the data encryption and decryption speed of the chip.