The invention discloses anti-salt high-density early-strength anti-channeling oil well cement slurry. The cement slurry includes oil well cement, iron ore powder, ultrafine cement, micro-silicon, manganese ore powder, and a styrene-butadiene latex anti-channeling agent, which are mixed according to certain ratio. The six components, in a manner of grain composition, are subjected to ratio optimization in density and granular size, wherein a high-anti-salt additive having cooperative performances is added to the components, so that the mixed cement slurry has stable main body performance and has excellent settlement stability. The components are mixed uniformly with semi-saturated salt water to form the cement slurry which is low in free water content and has good flowability, is micro-expansive and early-strength and has strong anti-channeling performance. Channel of oil gas and water due to annulus phenomenon caused by shrinkage of cement slurry can be prevented during hardening process of the cement slurry. The set cement slurry reaches 14 MPa in strength within 24 h, so that cementing time is shortened and furthermore well drilling period is reduced.