The invention discloses a production process for a directly-spun terylene industrial filament of a liquid-phase tackifying fusant, belonging to the technical field of spinning. The production process includes the following steps: esterification, polycondensation, liquid-phase tackification and spinning. The production process is characterized in that: in a vertical reaction kettle, liquid-phase tackfication is carried out on the fusant obtained through esterification and polycondensation of glycol and phthalic acid; the vertical reaction kettle adopts a tower type film forming structure; the fusant enters the vertical reaction kettle from the top part for distribution, and the film forming is naturally finished under the action of gravity; a backflow pipeline is provided for the discharging of the reaction kettle, the viscosity and flow rate of the fusant are controlled by the backflow adjusting, the intrinsic viscosity of the polyester fusant after being tackified in a liquid-phase manner is within 0.85 to 1.0dl/g, and the fusant is conveyed to a spinning box body by a gear pump for spinning. By reasonably designing the reaction kettle and allocating the process, the invention effectively solves the consistency between the fusant reacting condition and the staying time; meanwhile, the consumption of a public medium is reduced, and the cost is lowered; by optimizing the process, the invention increases the production efficiency of a system and improves the product quality.