A sensing pixel array is provided and includes a plurality of pixels disposed in an array. Each pixel operates during an exposure period and a readout period and generates a readout signal. Each pixel includes a sensing unit and a sampling unit. The sensing unit senses light to generate a sensing signal during the exposure period. The sampling unit samples the sensing signal to generate a sensing output signal which serves as the readout signal during the readout period. During the exposure period, the sampling unit acts as a memory unit for storing an input signal and outputting an accessed output signal which serves as the readout signal.