Effect of release height on atmosphere dispersion factor of radioactive effluent discharged from nuclear power plant was discussed in this paper. The atmosphere dispersion factor in nuclear accident was simulated by PAVAN model. Here, the effects of release height in two downwind distances as EAB and LPZ were considered. The results indicated that the atmosphere dispersion factor presented decrease trend with increased release height in two boundaries. The comparison of atmosphere dispersion factor in two boundaries also represented remarkable change impacted by the wind direction. The maximum and the minimum rates of descent of atmosphere dispersion factor with release height separately occurred in ENE and SE wind direction in two boundaries.