Abstract: Because the wellhead setting load for casing string has some defects in setting and control method during petroleum drilling engineering, the whole force condition of casing string has been analyzed, and with the uncertainty of the loaded force during the period of slurry cementing, wellhead setting load can not be calculated by this data, and related industry standard was defective too. This paper analyzed each factor that impacted and controlled the wellhead setting load, and found that when the load meets some certain interval requirement, it can be determined directly by making the load slightly heavier than the weight of free casing section. According to the force and deformation of free casing section in the process of slurry solid, a practice method of controlling the setting load was proposed: to calculate the real differential deformation length ΔL of non-consolidated casing section under two conditions: before slurry cementing and after setting, so before slurry cementing move the casing strings upward by length of ΔL; at the last stage of slurry injection, put the casing string and casing suspender onto the exactly position after the latest slurry cementing. This wellhead setting method is suitable for different well types and different kinds of casing suspender with one-stage or multistage slurry injection technique.