A deserializer for converting serial data into at least one parallel data includes a first flip-flop group, a second flip-flop group and a programmable frequency divider. The first flip-flop group includes a plurality of flip-flops connected in series, where the first flip-flop group is controlled by a first clock signal. The second flip-flop group includes a plurality of flip-flops, where the second flip-flop group is controlled by a second clock signal, and the flip-flops of the second flip-flop group are respectively connected to output nodes of the flip-flops of the first flip-flop group. The programmable frequency divider is coupled to each of the flip-flops of the second flip-flop group, and is utilized for receiving a control signal and generating the second clock signal by performing a frequency-dividing operation according to a frequency-dividing factor set by the control signal.