A new protection method is presented based on the non-characteristic third-harmonic current and the corresponding setting scheme is proposed. It analyzes application of the method and shows that the new protection can reliably act no matter what types of fault in protection zone except for single-phase to ground and its protection dead zone is less than the unbalance current protection. When fault occurs out of the protection zone and reaches the steady-state， the reliable no-action of protection can be ensured. The abnormal operation caused by the fault clearing or fault recovery may produce non-characteristic third harmonic， which can affect the protection. The time delay can be added to the protection to solve the problem. PSCAD simulation results show effectiveness of the presented protection.