Abstract: With the rapid development of offshore wind power industry, the construction of multiple offshore wind farms in small area has a cumulative effect on the marine ecological environment during a short period.Through the identification of cumulative impact and the investigation of wind farm construction in Binhai county, the accumulative effect of offshore wind farm construction on marine water quality, and marine organism were analyzed and evaluated by the methods of scene analysis, GIS technology and assignment calculation.The results showed that multiple offshore wind farm construction had a great cumulative effect on ecological environment of offshore areas and wind farm areas.The synthesis score of three scenes was 0.475, 0.508 and 0.640, which indicated the cumulative effect increased with the quantity and scale of wind farm.The results of assessment showed that multiple offshore wind farm construction had great effect on the marine ecological environment during a short period, so it is necessary to develop the offshore wind power in a reasonable and prudent way, strengthen construction management and take effective ecological compensation measures in this area.