The invention relates to the technical field of a crude oil predehydration device, and particularly relates to an ultraheavy oil high-temperature high-efficiency elevation-angled predehydration device; the ultraheavy-oil high-temperature high-efficiency elevation-angled predehydration device comprises a tank body, an effluent oil collector, a dehydration coalescer, an oil removal coalesce, and a sand washing device, wherein the tank body is low in left and high in right and oblique, the included angle of the tank body and a horizontal plane ranges from 9 degrees to 15 degrees; the effluent oil collector is fixedly arranged at the right part of the tank body, and a liquid inlet cavity is formed between the effluent oil collector and the right end of the tank body; a liquid inlet port is formed in the tank body on the upper part of the liquid inlet cavity; the dehydration coalescer is fixedly arranged in the tank body at the left side of the effluent oil collector at intervals, and a collecting vessel is formed between the dehydration coalescer and the effluent oil collector. The ultraheavy-oil high-temperature high-efficiency elevation-angled predehydration device is reasonable and compact in structure, and convenient to use; an elevation-angled separating tank body is adopted, so that the covering area of an oil-water interface can be enlarged, and the gas-liquid separation efficiency can be increased; the oil-water settling distance can be increased, and the oil-water separation effect can be enhanced; the high-efficiency separation in the limited tank body space can be realized, the separation effect is good, the separation precision is high, and the ultraheavy oil high-temperature high-efficiency elevation-angled predehydration device meets the oil-water separation demand of ultraheavy oil.