The invention relates to a multifunctional finishing agent and preparing method of nanometer composite water-clearing cloth with oil resistance, waterproof and sun-screening, which comprises the following parts: nanometer titanium dioxide, water-soluble acrylic fluorocarbon resin, cross linking agent, modifier, hygroscopic draining diaphoretic and water. The preparing procedure comprises the following steps: heating the weighed water; adding the titanium dioxide into the heating water; oscillating the solution by ultrasonic oscillator; stirring the solution at high speed to disperse the titanium dioxide entirely and uniformly; keeping 65 deg.c; adding the Ritter, Habolster and moisture absorption sequently to stir rapidly until dispersing; adding water-soluble acrylic fluorocarbon resin to stir rapidly until dispersing; immersing the cloth in the water-clear finishing agent for 2 minutes under normal atmospheric temperature; bailing, drying and putting into the 150 deg.c baking machine to generate product. The invention uses a basin clear-water to wash the clothes, which is widely used in the sports, blouse, uniform, field, fishery, architectural job clothes, window Holland, ad, sheet, car sunscreen cap and other domains.