A full-color active matrix organic electroluminescent device and fabrication method thereof. The full-color active matrix organic electroluminescent device includes a substrate with a plurality of TFTs, a buffer layer formed on the substrate beyond the TFTs, a color filter formed on the buffer layer, a flat layer formed on the entire surface of the color filter, a first electrode formed on the flat layer, an organic electroluminescent layer formed on the first electrode, and a second electrode formed on the organic electroluminescent layer, wherein the flat layer is formed by a low temperature thin film process.