A pixel driving circuit, comprising: a plurality of pixels arranged in a matrix; gate lines located between two adjacent rows of the pixels, at least one of the pixels comprising a light touch module which comprises: a photosensitive unit which senses the light intensity and produces an electrical signal carrying the light intensity information; a signal reading unit connected with the photosensitive unit, the signal reading unit being controlled by the gate lines, being turned on under the driving of the gate lines, and reading the electrical signal from the photosensitive unit; characterized in that said light touch module comprises: an amplifier connected with the signal reading unit, the amplifier acquiring the electrical signal from the signal reading unit and amplifying the electrical signal, a common end of the amplifier being grounded; a processor connected with the amplifier, a threshold of the change of the electrical signal and the electrical signal amplified at a previous time being stored in the processor, the processor being configured to acquire the electrical signal amplified at the current time from the amplifier, obtain a change amount of the electrical signal amplified at the current time relative to the stored electrical signal amplified at a previous time, compare the change amount with the stored threshold of the change of the electrical signal, acquire the position information of the pixel where the light touch module is located when the change amount is greater than the stored threshold of the electrical signal change, and take the position information as the touch position. a photosensitive unit which senses the light intensity and produces an electrical signal carrying the light intensity information; a signal reading unit connected with the photosensitive unit, the signal reading unit being controlled by the gate lines, being turned on under the driving of the gate lines, and reading the electrical signal from the photosensitive unit; characterized in that said light touch module comprises: an amplifier connected with the signal reading unit, the amplifier acquiring the electrical signal from the signal reading unit and amplifying the electrical signal, a common end of the amplifier being grounded; a processor connected with the amplifier, a threshold of the change of the electrical signal and the electrical signal amplified at a previous time being stored in the processor, the processor being configured to acquire the electrical signal amplified at the current time from the amplifier, obtain a change amount of the electrical signal amplified at the current time relative to the stored electrical signal amplified at a previous time, compare the change amount with the stored threshold of the change of the electrical signal, acquire the position information of the pixel where the light touch module is located when the change amount is greater than the stored threshold of the electrical signal change, and take the position information as the touch position. an amplifier connected with the signal reading unit, the amplifier acquiring the electrical signal from the signal reading unit and amplifying the electrical signal, a common end of the amplifier being grounded; a processor connected with the amplifier, a threshold of the change of the electrical signal and the electrical signal amplified at a previous time being stored in the processor, the processor being configured to acquire the electrical signal amplified at the current time from the amplifier, obtain a change amount of the electrical signal amplified at the current time relative to the stored electrical signal amplified at a previous time, compare the change amount with the stored threshold of the change of the electrical signal, acquire the position information of the pixel where the light touch module is located when the change amount is greater than the stored threshold of the electrical signal change, and take the position information as the touch position.