Polymer relies on its special properties, which is an effective means to enhance oil recovery. But the composition of its produced liquid is very complex, especially emulsifying phenomenon severely constrains the process oil-water separation at a later stage. At present technical means of demulsification taken by both home and abroad oilfield mainly include physics, chemistry and other methods. Currently there have been developed several new types of demulsifier including non-polyether polymer demulsifiers, amphoteric demulsifier, demulsifier plus chain extender, excluding epoxides demulsifier, complex type demulsifier, for the O / W emulsion breaker. Research on demulsifier mainly based nonionic polyoxyethylenepolyoxypropylene block polymer, the modification on the basis of the traditional demulsifier, its main research methods are: "changing the head, exchanging the tail, adding bone, and extending the chain, grafting, crosslinking, complex compound "and so on.