As fundamental equipment of advanced metering infrastructure (AMI), smart meters collect interval measurements from customer sites and thus provide system wide visibility for power companies. Considering the measurement characteristics of AMI, a series of integrated distribution state estimation methods for medium-voltage and low-voltage distribution network are put forward aiming at online or offline scenarios with 2 kinds of data collection methods respectively. Taking the modified IEEE 13-node test system as an example, the application of the offline scenario with data collected one by one is analyzed and testified. Numerical studies show that the proposed approach can achieve a higher accuracy level for estimation under a shorter cycle, which can provide more effective information for electric power companies.