The invention discloses a multifunctional textile fabric finishing agent and preparation and after-finishing methods thereof. The finishing agent comprises nano-fibers, dispersing agents, adhesives, coupling agents and water. The preparation method includes: weighing the polyaniline nano-fibers, the adhesives, the dispersing agents, the coupling agents and the water; heating the water, adding the polyaniline nano-fibers and the dispersing agents into the water and oscillating, dispersing and stirring the polyaniline nano-fibers by the aid of an ultrasonic oscillator until completely and uniformly dispersing the polyaniline nano-fibers; adding the adhesives and the coupling agents into slurry and continuing stirring; and realizing ball milling for the slurry by the aid of a ball mill to form the finishing agent. The after-finishing method includes: selecting a textile fabric and placing the textile fabric into multifunctional finishing agent solution; and soaking, drying and curing the textile fabric at normal temperature to form a microcirculation healthcare, warm and static-free finished product with anions after curing. The textile fabric has the performances of moisture absorption, sweat removal, air permeability, energy storage, heat storage and anion release, and is widely used for manufacturing undershirts, thermal wear, socks, bedding, military tents, knee pads, elbow pads, wrist supports, medical supplies and the like.