The invention discloses an SAR radar data encryption device based on an SOC chip and a method thereof. The device comprises an SOC chip with the integration of an FPGA IP and an MCU IP, a program FLASH memory connected to the FPGA IP, a configuration FLASH memory connected to the MCU IP, an RS-485 receiver connected to the FPGA IP, a first RS-485 interface connected to the RS-485 receiver, an RS-485 transmitter connected to the FPGA IP, a second RS-485 interface connected to the RS-485 transmitter, an RS-232 transceiver connected to the MCU IP, and an RS-232 interface connected to the RS-232 transceiver. According to the device and the method, the SOC chip with the integration of the FPGA IP and the MCU IP is employed, thus the work of data encryption, key management and interface communication is completed by using a single chip, the real-time encryption of the imaging data of an SAR radar system is realized, the system complexity is simplified, and the time and cost of system development are effectively reduced.