In order to control the water deterioration of Lake Hulun,using the water quality monitoring data of Kherlen River which is the main river into Lake Hulun in the wet seasons(from June to August) of 2010-2014 to study the pollutant influx of ammonia nitrogen, total nitrogen, total phosphorus and COD_Cr in detail.Single factor index method was used in water quality evaluation and the primary pollutant was found out by the equal standard pollution load in the estuary.Correlation analysis was used to study the relationship among water quality,water quantity and pollutant influx.The results showed that during the study period the water in estuary was polluted by total nitrogen and chemical oxygen demand seriously,all stayed in class Ⅴ or substandard V level.Total phosphorus was at a level of class Ⅲ to Ⅳ.Pollutant influx were increasing year by year and there was a slight decline in 2014.The equal standard pollution load of total nitrogen was the highest of all and became the primary pollutant in the estuary.There was certain positive correlation between water quality and water quantity in the estuary.Water quantity was the key factor affecting the pollutant influx,while water quality was the main factor.At present,control the influx of TN and COD_Cr is the primary task.Reasonable controlling of grazing and making the wastewater of town up to the discharging standard after processing are imperative to reduce the water pollution of river and lake.