Abstract: The study of network health of distribution system is of significant value for network condition-based maintenances. In order to quantitatively assess the network performance of distribution system, a new health index (HI) model of distribution network is proposed based on assets condition. The idea of Goal Oriented (GO) method is introduced into the health evaluation of distribution networks by converting the health index of distribution equipment into probability forms. And the relative complex structure is analyzed using network-equivalent method. Moreover, five typical cases are simulated in the 4th feeder of IEEE RBTS-Bus2 system. As a result, the theoretical analysis and simulation results show that this method is logically clear and easy to be programmed on computer, which provide a feasible solution for quantitative evaluation of whole health performance for distribution power network.