Abstract: The paper gives the detailed instruction on the data acquirement of the valid cells of Acoustic Doppler Current Profiler(ADCP)near bed1 According to the analysis of the vertical distribution of the signal amplitude with the extremum theorem,the location of the bed is fixed and the velocity data are extracted which was once lost due to the disadvantage of ADCP software and the errors of the bottom track algorithm. The validity of the extracted data is verified by using the synchronous data with the same depth of electric current meter. The data acquirement of valid cells of ADCP near bed provides a kind of convenient and effective measurement of the velocity near bed and enriches the vertical velocity data,too.