In power systems mainly consisting of thermal units， the time for units' start-up and restoration determines the duration of network reconfiguration following large-area blackout. Centralized-operation simulator for power plant is first employed to investigate the starting process of thermal units thereby establishing the relationship between start-up time and the cumulative downtime corresponding to typical unit types. Based on this， a parallel restoration strategy is proposed for reconstructing a power network. According to this strategy， the unit nodes are regarded as the load nodes with the highest priority and while being processed together with other load nodes. After available crank power in each stage is used as constraints， parallel restoration paths are optimized with Prim algorithm. Case studies with the IEEE 30-bus system verify that the reconfiguration scheme achieved can make full use of the crank power thereby restoring multi units and paths simultaneously so that the duration is reduced effectively. This is essential for organizing restoration scenarios rapidly and systematically following a large-scale blackout.