An OLED substrate and a packaging method and a display apparatus thereof are provided. The method for packaging the OLED substrate includes: forming a functional layer having a slit on a substrate where a pixel defining layer and an OLED device are formed, the slit corresponding to a pattern location of the pixel defining layer; etching the pixel defining layer by using the functional layer as a mask to obtain the pixel defining layer having a groove; and forming a packaging thin film on the pixel defining layer having the groove and the functional layer to obtain a thin-film packaging layer sinking into the groove.