To achieve the effective scale removing technology in water-gathering pipelines，the scale of pipelines and ionic composition of produced water at L95 production sites in Linpan oilfield were analyzed. The interaction between Ba²⁺ and Sr²⁺ of produced water and scaling mechanism in scaling process was studied. The results showed that the scale was composed of barium sulfate and strontium sulfate in molar ratio 1∶1. The produced waters from five wells were rich in Ba²⁺ and Sr²⁺，such as L95-1 and L95-36 well，and other three wells were rich in SO₄^2- and Sr²⁺，such as L95-18 and L95-12 well. Mixing these two types of produced water would lead to scale formation in gathering pipelines. When the concentration of SO₄^2- was 1620 mg/L，barium sulfate scale was easy to form，while strontium sulfate scale was difficult to from. The concentration of Sr²⁺ had little influence on the scaling rate of barium sulfate scale，while the scaling rate of strontium sulfate scale increased obviously with increasing Ba²⁺ concentration. Thus，the effect of Ba²⁺ on strontium sulfate scale formation was a major cause of serious scaling in water-gathering pipelines of L95 production sites. After mixing these produced waters from various L95 production wells in a device for scale formation，the total scaling rate of barium and strontium sulfates scale was 89.87%—92.35% with enough SO₄^2-. The remaining Ba²⁺ and Sr²⁺ could not lead to the scale formation in gathering pipelines.