Provided are an organic light emitting diode display device and a manufacturing method thereof. The method includes: preparing a thin film transistor layer on a glass substrate; preparing an organic light emitting diode element layer on the thin film transistor layer, and preparing a barrier layer and a buffer layer on the glass substrate, wherein the barrier layer covers the OLED element layer; preparing the plurality of grooves in the barrier layer, and preparing a water absorbing material layer in the plurality of grooves. The permeability of water and oxygen is reduced for lowering the risk of breakage of the barrier layer and the buffer layer, and improving the service life of the OLED display device.