Aiming to meet the demand of radial active distributional network (ADN) for protections, an adaptive protection scheme based on directional interlocking principle is proposed. First, according to the tree-structured feature of distribution network, the setting rule for reference direction is defined. Combined with the interlocking direction rule, the proposed scheme can adapt for fault elements such as line, bus, etc. Next, after the network reconfiguration, the reference direction can be re-configurated automatically through the topology analysis. Furthermore, aiming to cater to the features that the ADN has high penetration of renewable energy and need to run in isolated island mode, full-impedance relay is choiced as the starting element to improve the sensibility of the protection. In order to solve the weak source problem that often occurs in ADN, a transfer-trip feature is adopted. The proposed scheme is verified using test cases based on a real distribution network, showing that it is easy, economic and reliable, and can provide a main protection scheme for ADN.