Abstract: According to the technical challenges in deepwater well cementing,such as low temperature,soft seabed,shallow water flow,and etc.,new types of deepwater cementing additive PC-DA92S,PC-DA93L and PC-DG72S with monomer complex technical have been developed.According to the actual well conditions in South China Sea,suitable cement slurry system for field application has been developed.Properties of this cement slurry system under deep water has been analyzed and evaluated.After being applied in Well LH16-1-1 in the South China Sea,it showed that the two cement slurry systems were characterized by early strength at low temperature,low fluid loss,good anti-gas channeling ability,ease in adjusting the thickening time,stable cement slurry system,and etc..So,it can be used for deepwater cementing of surface casing.