Distributed photovoltaic device in distribution network has the feature of wide distribution and strong intermittency. Its local consumption characteristic causes unbalanced distribution of carbon reduction contributions in distribution network. In order to measure the carbon reduction effect of distributed photovoltaic and energy storage devices in distribution network fairly,real lossy network is transformed into lossless virtual network through two-direction network loss allocation,and then the carbon emission flow distribution under a time section is obtained. Then,the carbon flow distribution corresponding to the planned power and actual power of distributed PV in longtime scale is calculated respectively to obtain the relative carbon emission intensity of distributed PV. Finally,the relative carbon emission intensity of distributed photovoltaic under different distribution network energy storage capacity scenarios is calculated,which is the basis of carbon reduction effect measurement of energy storage devices,so as to propose a carbon reduction contribution distribution method in distribution network including photovoltaic and energy storage devices that meets the principle of fair distribution,and the standard calculation example is verified.