The invention provides an online analyzing and calculating parallel programming auxiliary system and a debugging method thereof for a large power grid. The system comprises a parallel calculating cluster and a large power grid online analyzing parallel programming work station which are communicated with each other through a Socket access interface; the parallel calculating cluster comprises n servers equipped with domestically produced Linux systems, wherein each server comprises a debugger and a developing debugging service module. The large power grid online analyzing parallel programming work station is a computer terminal used by developers for programming and debugging parallel programs, wherein the parallel programming work station comprises an auxiliary system bottom layer service module and a cross-platform auxiliary human-computer interface which are communicated through an API access interface. The system is tightly combined with a large power grid parallel programming model so that the parallelization efficiency of large power grid online analysis is effectively increased.