Abstract: Taking Qinhuangdao-Beijing Oil Pipeline and Renqiu-Beijing Oil Pipeline as examples, influence of thermometry system's precision on fuel oil consumption of heater is analyzed.The author points out that it is an important link to increase the precision of thermometry system in decreasing energy consumption.Cause analysis on precision degradation of thermometry system is made from thermometry performance and ambient condition.Technical measures in periodic examination, check-up and correct the wrong installation way of instruments are presented.