The invention provides a method for producing industrial polyester filament by recycled PET (Polyethylene Terephthalate) bottle chips on a scale. The method comprises the steps of crushing the recycled PET bottles into chips, washing and drying, sending into a crystallization bed body for crystallization, forming crystallization layers on the surfaces of the bottle chips, sending the crystallizedbottle chips into a drying tower which is provided with a pair of spiral agitators, leading the dried bottle chips to enter a screw extruder for melting and extrusion, sending the obtained melt into a two-stage filtration device consisting of a coarse filter, a fine filter and a pressure pump between the coarse filter and the fine filter for filtration, leading the melt which is filtrated by two stages to enter a liquid phase tackifying kettle, conducting polycondensation reaction in the liquid phase tackifying kettle, leading the melt after being subjected to liquid phase tackifying to entera spinning box, and spinning by adopting a high-speed spinning process, thus obtaining the industrial polyester filament. In the method for producing the industrial polyester filament, the liquid phase tackifying step is added in the production process, so that the problems of low viscosity and poor stability of the PET bottle chip melts are solved.