Provided are a pixel of an uncooled infrared focal plane detector and a preparation method therefor. The pixel includes a structure of three layers sequentially located on a semiconductor substrate from bottom to top. The first layer is a bridge structure including a metal reflection layer, an insulation dielectric layer, a first supporting layer, a first support layer protection layer, a first metal electrode layer and a first silicon nitride dielectric layer. The second layer is a thermal conversion structure including a second support layer, a second support layer protection layer, a thermal sensitive layer, a thermal sensitive layer production layer, a second metal electrode layer and a second silicon nitride dielectric layer. The third layer is an absorption structure including a third support layer, an absorption layer and an absorption layer protection layer.