The invention relates to a controllable multiple-differential-shrinkage composition fiber made from a copolyester melt through ultra-fast direct spinning, and a preparation method of the composition fiber. The copolyester melt, which is made from five components including terephthalic acid, ethylene glycol, poly ethylene glycol, diethylene glycol and pentaerythritol, is pressurized by a booster pump and transported through a melt pipeline into a spinning box body, and is then divided by two measuring pumps into two branches, which enter a spinning component and a spinneret respectively and finally be extruded. After cooling and curing, two yarns are formed, wherein one yarn is subject to oiling by an oil wheel, pre-entwining, stretching and thermoforming to obtain an FDY yarn, and the other yarn is subject to oiling by an oil nozzle, and is guided to two spinning discs to obtain a POY yarn; the two yarns are simultaneously input into a doubling device and a main entwining device for combination, and are formed through the ultra-fast rolling, so as to obtain the composition fiber. The composition fiber has the characteristics of relatively good micro three-dimensional morphological structure, moisture absorption property, moisture preservation property, air permeability and antistatic property, easiness in dyeing, uniform dyeing, high coloration uniformity and the like; the composition fiber is high in processing speed, high in yield, low in consumption, low in manufacturing cost, high in value added, high in product functions, good in quality, and obvious in advantage of performance price ratio.