Abstract: Self-healing is a distinguishing feature, by which the smart distribution network differs from traditional distribution network. To improve the practical level of various self-healing technologies it is necessary to accurately master overall immunity level of smart distribution network. For this reason, learning from the mechanism of human immune system, an immune system for smart distribution network, in which five immune functions such as immune tolerance, immune self-stabilization, immune recognition, immune response and immune recovery were included, was proposed. On this basis, a method to build an immunity assessment model based on the combination of the improved analytic hierarchy process (abbr. IAHP) with technique for order preference by similarity to ideal solution (abbr. TOPSIS) was put forward, and an immunity evaluation index system for smart distribution network and an immunity evaluation model for smart distribution network were constructed. The constructed evaluation model can overall consider various kinds of factors impacting the strength of immunity of smart distribution network and provide theoretical reference for elaborative operation, maintenance and management of smart distribution network in practical application.