By classifying the protection information and service，simple bus protection is realized in the process level network and station level network based on IEC61850.To improve the reliability of the acquisition system，double configuration of the merging unit and the point-to-point networking mode for the process level are used.To improve the reliability of the station level network，the communication redundancy with binary star bus architecture is designed.Internal and external faults in the protected areas，as well as communication network faults are simulated on the closed-loop real time digital simulator（RTDS）test platform，and the reliability of simple bus protection is demonstrated in detail.