A touch pixel array substrate suitable for a touch display panel includes a first substrate, scan lines, data lines, signal-control lines, read-out lines, voltage-shielding lines, active devices, pixel electrodes, and photo-sensing units. The scan lines, the data lines, the signal-control lines, the read-out lines, and the voltage-shielding lines are located on the first substrate. Each of the read-out lines is located between two adjacent data lines. Each of the voltage-shielding lines is located between one of the read-out lines and one of the data lines. Both sides of each of the read-out lines are adjacent to two voltage-shielding lines. The photo-sensing units are located on the first substrate and electrically connected to the scan lines, the signal-control lines, and the read-out lines correspondingly. A touch display panel and a touch pixel structure are also provided.