Given the problems of high-speed transmission and real-time processing of outdoor installation protection testing data in a smart substation, a test model of multiple sub machines in a High-Availability Seamless Redundancy (HSR) loop network is analyzed, the requirements of packet types, size and transmission speed are evaluated, and a hardware solution based on a multi-core Digital Signal Processor (DSP) is designed. In the software implementation, the tasks are decomposed and mapped to each core for parallel processing, and testing data are shifted quickly between cores by Inter-Processor Communication (IPC) interrupt and shared memory. Packet data are transferred at a high rate based on Serial RapidIO (SRIO). Testing and verification are performed for the organization and buffered packages, transmission speed and reliability. The results show that the performance of multi-core DSP meets the requirements of data process and throughput in outdoor installation protection testing. This work is supported by Science and Technology Project of State Grid Zhejiang Electric Power Company Ltd. (No. 5211DS18002T) and Science and Technology Project of State Grid Corporation of China (No. 5100-201946264A).