Abstract: Based on salinization of water channeled from Yellow River being stored in the Beidagang Reservoir and the mass transfer theory,it qualitatively analyzed that the main salinization mechanisms are the salinity transfer of saline soil,the evaporation concentrating and the agitation of wind.A simulation trial pond was built beside the reservoir and some researches were done Based on water and the solute balance in the simulative pond,the proportions of water salinization by salinity transfer of saline soil and the evaporation concentrating are calculated quantitatively.It was showed that the proportion of salinity transfer of the saline soil increased with time more than 30 days and that the proportion of salinity transfer of the saline soil remained 80% and evaporation concentration is 20% after 30 days.This indicates that salinity transfer of the saline soil is the most important one of all factors of the water salinizaion.