This thesis proposes an ultra low power 8-1 analog multiplexer (MUX) which can deal with low voltage amplitude and low frequency bio-signals, the analog MUX is implemented based on IBM 130 nm integrated circuit technology.Also a bio-signal amplifier with low power consumption, high CMRR, and high gain is connected to the output port of the multiplexer. In this way, the bio-signals can be easily detected and selected. For the analog multiplexer design, a parallel transmission gate structure is used to select the desired signal while keeping the power consumption of the eight-channel analog multiplexer to 807nW. For the amplifier design, a three-stage differential operational amplifier structure was used to amplify the weak of bio-signals passed through the transmission gate structures. The amplifier was designed with a high CMRR 106dB and reasonable gain of 66dB.