In view of the high concentration of hydrogen sulfide in water injection system of an oilfield in Bohai Sea，the modified triazine liquid desulfurizer and polyphosphate scale inhibitor were selected by measuring the desulfurization efficiency of desulfurizer on injected water and the effect of scale inhibitor on calcium ion concentration in injected water. Furthermore，the field pilot test was carried out on platform C where was the location of water injection well. The results showed that the desulfurization efficiency of modified triazine liquid desulfurizer for injected water was 98.1%，and the desulfurization effect was the best，but the concentration of calcium ion in water would reduce and scaling would occur. While used with polyphosphate scale inhibitor，the deposition of calcium ion could be significantly reduced. During the pilot test of the platform，the dosage of desulfurizer and scale inhibitor was 500 mg/L and 20 mg/L respectively. The concentration of hydrogen sulfide in the water source well system reduced from 800 mg/m³ to about 20 mg/m³，and the amount of hydrogen sulfide in the production fluid reduced from 150 mg/m³ to about 4mg/m³，which met the desulfurization requirement of the platform and avoided depositing scale.