The invention relates to the technical field of production of fiber products, in particular to a production method of ultralow shrinkage bright FDY. Light polyester melt is taken as the raw material and is delivered to a melt cooler, the melt is delivered to a spinning manifold after cooled by the melt cooler, the melt is extruded after metered by a metering pump and filtered by a spinning component in the spinning manifold, a spinneret plate is deigned in a special three-leaf shape, the fiber cross section is in a regular triangle shape, after spin is cooled by lateral blowing process, a tow enters a winding oil wheel for oiling, pre-interlacing, double roller heating, double roll shaping, main interlacing and rear heating plate heating are performed, and finally package molding is performed. According to the production method of the ultralow shrinkage bright FDY, a full drawing bright FDY product with the waste water shrinking percentage lower than 3% is produced on conventional bright FDY equipment.