The acquisition and processing system of biological signals, which has invoked the technology in computer, digital signal processing and skill of life-sciences experiment, has replaced the amplifier and recorder used before.

At present,biological signal acquisition and processing systems were gradually used in Chinese medicine research,which plays a role in the level of Chinese medicine research and improves theoretical science standardization of our country.

This paper mainly introduces a method of measuring the peak value of bioelectrical signals, expatiates on the structure, testing result, analysis for error and measure taken for improvement of the circuit designed by this method.

In order to detect and study the bioelectrical signal in-depth and overcome the problem of low dynamic range.

The simplyfied structure of the cell,the chemical constitutes of the membrane,and the mechanism of the bioelectric signal generation are included.

A subroutine used for fast displaying of bioelectric signal in EGA or VGA is described in this paper.

Due to its relative low amplitude properties,the bioelectricity signal is easy influenced by surrounding factor,the amplifier with low noise and voltage offset is required.

This paper discusses a method that uses a measuring amplifier to extract faint bioelectricity signal from strong interferences, and uses OrCAD PSpic.