A pixel array substrate including a substrate, multiple insulation patterns, multiple signal lines, and multiple pixel structures is provided. The insulation patterns are disposed on the substrate, and each has at least one recess structure. The signal lines are respectively disposed on the insulation patterns and are respectively filled in the at least one recess structure of one of the insulation patterns. The pixel structures are disposed on the substrate and are electrically connected to the signal lines. A pixel array substrate further including multiple conductive patterns is also disposed.