When an external fault of busbar occurs, the current transformer(CT) of non-fault phase is saturated.In order to prevent the busbar protection from mal-operating, the method to identify the non-fault phase saturation of the faulty branch based on the current distribution coefficient is proposed.After identifying the non-fault phase saturation, the busbar protection is blocked.The method calculates the external fault phase current distribution coefficient of the power branch and the secondary fault phase current distribution coefficient of the power branch, and compares the calculation results of the two current distribution coefficients.If the calculation results are inconsistent, it means that the secondary fault is saturated by the non-fault phase.If the calculation result is consistent, it means that the secondary fault is internal or external.The real time digital simulation(RTDS) results show that the method can quickly and accurately identify the non-fault phase saturation of the faulty branch without reducing the operating speed of the busbar protection, and reliably prevent the busbar protection from mal-operating.