Abstract: Wax-oil gels may be formed in a waxy crude oil pipeline when oil temperature decreases below cloud point. The characteristics of these gels are strong functions of shear and thermal histories. The gelation temperature decreases with cooling rates decreasing and shear stress increasing, while cloud point is independent of the cooling rates and shear stress. When ambient temperature reaches over the oil temperature, if oil temperature decreases below the cloud point, wax-oil gels can not be formed. The yield stress of a wax-oil depends on the amount of precipated particles and on the sizes of the crystals.