Abstarct: These days, increase in electricity consumption and limited capacity of power plants along with considerations of investment and electricity costs, have caused to the development of ways to make more exploitation of the facilities available. Conservation voltage reduction is one of the novel phenomenon which is proposed to decrease power consumption, losses and peak load in distribution systems by reducing the voltage of the distribution system to the lowest possible level of the permissible range (0.95 to 1.05 per-unit of nominal amount of voltage). Distributed generation is also a subject with many proven advantages including power loss reduction, network capacity release and qualitative improvement of voltage profile, and in the recent years it has been apprecated by electrical industry planners. In the concept of a conservation voltage reduction, it is found that when the voltage profile of the distribution system is flat, conservation voltage reduction will be more effective, also the nature of the distributed generation tends to form a flat voltage profile. The integration of the goals and results of the method of conservation voltage reduction and distributed generation units will create a positive overlap in order to achieve optimization objectives and improve the efficiency of the power system. In this research, with regard to ZIP-load model, the optimal placement of distributed generation using the particle swarm optimization algorithm are carried out in order to achieve the objectives of the objevtive functions with different types and combinations and then conservation voltage reduction is implemented. ZIP load model coefficients are obtained by field measurements and calculations. In order to show the effect of distributed generation on the conservation voltage reduction, the above process is implemented on a 33-bus sample distribution system and obtained results will be examined in different scenarios.