A structure of a thin film transistor (TFT) planar display panel is disclosed. The structure includes a light-transmissible substrate, a buffer layer formed on the light-transmissible substrate, a top-gate TFT structure formed on the buffer layer and including a channel region, and a light-shielding structure formed between a back light source and the top-gate TFT structure, and substantially aligned with the channel region for protecting the channel region from illumination of the back light source. The process for manufacturing a TFT planar display panel is also disclosed.