The access of unmeasurable load branch had an impact on the protection of distribution network. So this paper designed a differential protection scheme based on the similarity of bilateral currents. The current characteristic of active distribution network with unmeasurable load branches in different fault places was analyzed. On this basis, Euclidean distance was used to measure the similarity of the currents on both sides, so that the braking coefficient can be modified adaptively with the fault location. It used PSCAD to verify the scheme, and the results show that when different unmeasured load branches accessed, the braking coefficient would decrease to 0 in case of in zone fault or increase to 0.87 in case of out of zone fault, so as to realize that the current differential protection could operate correctly. Therefore, the influence of unmeasured load branches on distribution network protection is avoided.