There are various hardware platforms of line protection devices nowadays， several of these popular hardware architectures being described. Considering the application of digital substation standard IEC 61850， a new platform of line protection based on an embedded real-time operating system is proposed with the hardware and software architectures of protection module and management module discussed in detail. The network and fiber-optical communication techniques are adopted in the platform to not only satisfy the requirements of future development of the line protection， but also to reuse the hardware and software architectures of the above two modules to a great extent， greatly reducing the design workload.