The invention relates to an underpants type paper diaper and a preparation method thereof in the field of disposable hygienic products, the underpants type paper diaper comprises an absorption main body and an outer packing body, a liquid-permeable
surface layer material of the absorption main body is a
composite surface layer material, and the
composite surface layer material is formed by connecting at least two
layers of non-woven fabrics through connecting points. The upper-layer non-
woven fabric is provided with protruding parts protruding upwards from the joint points, the protruding parts and the joint points are alternately and regularly arranged, the inner sides of the protruding parts are sprayed with
camellia oil slow-release capsules, and flow guide holes smaller than the joint points are formed in the joint points. In the process of using the underpants type paper diaper provided by the invention, the
camellia oil sustained-release capsules on the inner sides of the convex parts of the liquid-permeable
surface layer can be released, so that the
skin of a wearer can be effectively moistened, a sebum film on the surface of the
skin can effectively exist, and adverse reactions such as
allergy, chapping, roughness,
diaper rash and the like are reduced.