Based on a known initial steady-state case，a class direct current（DC）power flow algorithm with higher calculation accuracy is proposed.It is suitable for topology invariant operating conditions where only the power injection changes.Compared to standard DC power flow，this algorithm only needs to solve a group of correction factors based on the known initial case.Simulation results of several IEEE standard systems and the Polish power grid show that when the power injection change is in the range of-30%～60%，the class DC method is much better than standard DC method in power flow calculation with an accuracy of more than70%improvement.