Abstract: The integration of high proportion of distributed photovoltaic（PV） into distribution networks can lead to a series of problems such as reverse power flow and voltage violations, posing a serious threat to the safe operation of distribution networks.This paper introduces the theory of moment difference analysis for distributed PV distribution networks, transforming the problem of distributed PV accommodation in distribution networks into a balance problem of restoring and maintaining moment difference equations. For a given distribution network, when the maximum node voltage reaches the specified voltage upper-limit, the moment difference between PV moment and load moment, termed as critical moment difference, approximates to a constant. The critical moment difference represents the ability limit of a distribution network in accommodating distributed PV, where PV moments are the entities that need to be accommodated in distribution networks, and load moments serve as resources for accommodating PV moments. Based on the moment difference analysis theory, the PV curtailment minimizing decision for distributed PV in distribution networks is proposed and applied to the analysis and calculation of a 10 kV single-branch distribution line, and a 12.66 kV multi-branch distribution network in the IEEE 33-node system. Results of the case studies show that the proposed PV curtailment minimizing decision improves the optimization speed by 2 877 times under the condition of an error of no more than 1.2%, verifying the correctness and rapidity of the method.