Abstract: Based on the national standard，the monitoring method of ⁹⁰Sr and ¹³⁷Cs in the environmental water was improved, such as increasing the sampling(50-100 L), selecting effective precipitant and low level detector. ⁹⁰Sr and ¹³⁷Cs in the water(50-100 L) were measured using the improved method. Results show that the concentration efficiency of ⁹⁰Sr and ¹³⁷Cs are (91.3+2.8)% and (97.2+1.4)%. The full recovery of ⁹⁰Sr are 81.5%±2.8%. The minimum detectable limit of ⁹⁰Sr and ¹³⁷Cs are 8.6×10^-4 Bq/L and 9.8×10^-4 Bq/L respectively. The comparison results about ⁹⁰Sr in the water(50 L) show that the relative deviation of measured value of four units and the nominal value is less than 11%. The results show that this method is applicable to monitoring trace of the radioactive in the environment water and can meet the requirements of environmental background survey and environmental monitoring.