In the field operation，when testing the solid phase content of drilling fluid，it was found that the measured value of solid phase content of drilling fluid with formate was seriously deviated from the real situation. According to the volume fraction of solid phase，the measured result was generally higher than the actual value by 3%—8%. Furthermore，the higher the formate content， the higher the deviation degree was. The commonly used salt content correction means were no longer applicable to the drilling fluid system containing formate. Based on the K⁺ content value，the author established the relationship between K⁺ content and HCOOK content，HCOOK content and the measured value of drilling fluid solid phase，HCOOK content and the change of liquid phase density of the system，and the relevant quantities of solid phase composition analysis through data fitting，so that the solid phase content correction calculation could be carried out for drilling fluid with HCOOK added. Considering that both KCl and HCOOK were often used in field operations to increase K + required by drilling fluid system，the type of salt that provides K + could be determined by the principle of ion balance based on the Cl- content measurement and analysis data in drilling fluid operations and the background value of formation salt content. In actual construction，K⁺ was always in the dynamic change of“consumption-supplement”. In order to better analyze and judge the change of K⁺ quantity combined with actual construction information，the calculation method of K⁺ consumption was given in this paper，which could be used as a reference for on-site drilling fluid maintenance and treatment. The processing results of the measured solid content data showed that the data analysis and processing method provided in this paper could effectively eliminate the error in determination of the solid content of drilling fluid containing formate.