The invention discloses a multi-stage reliability improving method of distributed power supply-contained distribution networks. The method comprises the following steps: collecting power supplying reliability and user average power failure time of distributed power supply-contained distribution networks; according to the power supplying reliability and user average power failure time, carrying out stage classification on distribution networks, and determining the distribution network of which power supplying reliability is greater than 99.980% and the average power failure time is less than 1.8 hours to be in a distribution network structure maturity period, the distribution network of which power supplying reliability is greater than 99.9100% and the average power failure time is less than 8 hours to be in a network work structure development period, and the distribution network of which power supplying reliability is greater than 99.8300% and the average power failure time is less than 15 hours to be in a distribution network structure construction period; and on the basis of the three different distribution network structure stages, respectively improving distribution network reliability in the terms of network, equipment, technology and management. With the method, the energy is saved and the distribution network operation efficiency is improved.