The invention relates to a flexible attapulgite membrane and a preparation method thereof. Attapulgite is the matrix of the membrane, and water soluble polymer is the additive, and the mass ratio of attapulgite to water soluble polymer is 100:1-6. The preparation method comprises the following steps: dispersing attapulgite membrane into water, adding diluted acid, stirring, filtering, washing the membrane to neutral, drying, grinding, sieving, dispersing the powder into water, subjecting the solution to an ultrasonic treatment, separating to obtain attapulgite suspension; dropwise adding a water soluble polymer solution into the attapulgite suspension under stirring, blending and stirring to obtain blended suspension; filling the blended suspension into a mould, and evaporating the suspension in the mould at a constant temperature of 40 to 70 DEG C so as to obtain the flexible attapulgite membrane. The provided preparation technology is nontoxic and harmless. The prepared flexible membrane is flexible, has high thermal stability and a good absorbing performance, and can be applied to the fields such as air purification, waste liquid filtration, and the like.