For the wastewater pretreatment system of Daniudi gasfield, scaling in wastewater pipelines is a big problem severely affecting a normal operation. So, we first analyzed the component of both water and scale, and pointed out that the scale is dominantly by calcium carbonates. Furthermore, we analyzed the scaling tendency and its influencing factors by means of two methods of saturation index and stability index. Results show that the main reasons why scaling may occur in pretreatment pipelines contain pH value and temperature increase. Finally, through some technical optimization, the temperature and pH value after pretreatment decreased to 5 ℃~10 ℃ and 7, respectively. In result, the scaling might be evidently inhibited and period of acid cleaning postponed from 2 months to 4 months.