The invention discloses low-temperature instant flexible sheets and a preparation method thereof, belongs to the technical field of fabric dyeing and finishing, and particularly relates to the low-temperature instant flexible sheets. The low-temperature instant flexible sheets are characterized by being prepared from the following raw materials in part by weight: 60 to 65 parts of stearic acid, 10 to 15 parts of hydroxyethyl-ethylenediamine, 9 to 16 parts of diethylenetriamine, 3 to 5 parts of urea, 5 to 7 parts of methyl carbonate, and 4 to 8 parts of acetic acid. The method comprises the following steps of: adding the hydroxyethyl-ethylenediamine and the diethylenetriamine into the stearic acid for amidation reaction; increasing the temperature to ensure that the amidated diethylenetriamine is cyclized to generate tertiary amine with an imidazoline structure; then using the methyl carbonate and the acetic acid as an alkylating reagent to make the tertiary amine become imidazoline quaternary ammonium salt; adding the urea to remove NH3 in two secondary amines in the amidated hydroxyethyl-ethylenediamine to form a hydroxyl cross-linking compound; then taking the acetic acid and the methyl carbonate as the alkylating reagent to make the compound have a quaternary ammonium salt structure; and then cooling to cut into slices to obtain the low-temperature instant flexible sheets. The prepared low-temperature instant flexible sheets have good permeation, detergency, emulsification and dispersion properties.