The invention discloses a testing method for the
water vapor penetration rate of a thin film. The testing method comprises the following steps: S1, evaporating a
calcium thin film layer on a substrate; S2, depositing a packaging thin film layer on the substrate through an
atomic layer deposition layer under protective gas, enabling the
calcium thin film layer to be covered with the packaging thin film layer to obtain a thin film device to be measured; and S3, testing the thin film device to be measured obtain in the step S2 by adopting a
Kelvin four-probe method, obtaining a time-varying
conductivity curve of the
calcium thin film layer in the thin film device to be measured, and extracting the slope of a linear part of the curve: d(1 / R) / dt, and substituting into a next formula as shown in the specification to obtain the
water vapor penetration rate of the thin film eta WVTR, wherein in the formula, n is
water vapor penetration characteristic coefficient at the temperature of 25 DEG C, M(H2O) is the
molar mass of water, M(Ca) is the
molar mass of calcium,
delta is calcium
specific resistance, rho is calcium density, L is the length of the calcium thin film layer, and W is the width of the calcium thin film layer. The test precision can reach 1 * 10<-6> g * m<-2> * d<-1>, and the test method has the advantages of being quick, simple, high in accuracy and the like.