The settlement stability of cementing slurry is one of the important indicators of cement slurry construction performance. With the more complex well conditions such as deep wells and ultra-deep wells，especially in recent years，the well depth is extended to 10 000 meters，therefor the temperature of the bottom of the well will reach more than 240 ℃. Consequently，it poses a challenge to the stability of cementing slurry. Previously the suspending agents can improve the suspension stability，but reduce the rheological property of cementing slurry，which is detrimental to well cementing under complex well conditions. By summarizing the research status of oil well cement suspension，the main types and mechanisms of suspending agents were systematically discussed. Additionally，the optimization of current suspension agents was analyzed，including the optimal compounding of inorganic and organic polymer materials，the optimization of comonomers，as well as the graft copolymerization，which would provide reference for research of oil well cement suspension.