The application discloses an air absorption film and a preparation method thereof, relates to the field of
film coating, and aims to solve the problem of avoiding the decrease of vacuum degree of a VC cavity, and the technical scheme is as follows: a substrate is subjected to first layer film deposition, the target material is a NiV
alloy target with a purity of 99.95%, or a
NiCr alloy target with a purity of 99.9%, or an AgNi
alloy target with a purity of 99.99%; then, second layer film deposition is carried out, the target material is a Pd target with a purity of 99.95%; then, third layer film deposition is carried out, the target material is a TiZr
alloy target with a purity of 99.9%; then, fourth layer film deposition is carried out, the target material is a Pd target with a purity of 99.95%; then, fifth layer film deposition is carried out, the target material is a TiZr alloy target with a purity of 99.9%; then, sixth layer film deposition is carried out, the target material is a Pd target with a purity of 99.95%; and then, seventh layer film deposition is carried out, the target material is a NiV alloy target with a purity of 99.95%, or a
NiCr alloy target with a purity of 99.9%, or an AgNi alloy target with a purity of 99.99%. The air absorption film and the preparation method thereof can guarantee the performance of the VC cavity.