The invention discloses tung oil polyhydric-alcohol-based nonionic polyurethane capable of being crosslinked later and a preparation thereof, and belongs to the technical field of polymer synthesis. A mixture (MDI-50) of conjugated double bond containing tung oil polyhydric alcohol (or called hydroxylated tung oil (HTO)) subjected to alcoholysis or aminolysis, polyethylene glycol (PEG) and 4,4'-benzhydryl diisocyanate / 2,4'-benzhydryl diisocyanate or 4,4'-hexamethylene diisocyanate (HMDI) and the like are adopted as raw materials, the reaction conditions are controlled to make the raw materials including reactive hydrogen react with isocyanate by controlling reaction conditions, viscosity is controlled, and nonionic polyurethane dispersion liquid (HTO-NPUD) which has hydrophilic units and oleophilic units at the same time, comprises a conjugated double bond structure, and can be stable in all pH values is generated. Compared with common polyether type nonionic polyurethane, nonionic polyurethane containing three tung oil conjugated double bonds can be stable in an acid-base medium, the surface tension is obviously reduced, HLB can be adjusted according to the content of a hard segment, and the tung oil polyhydric-alcohol-based nonionic polyurethane is expected to serve as a functional type nonionic polyurethane stabilizing agent, and is used for preparation of polyurethane alloy.