Abstract: The traditional methods of microbial detection usually have shortcomings including cumbersome steps,consuming time and high cost,so developing rapid and effective detection of new technologies and methods for microbial detection is particularly necessary.In this paper,whole-cell SELEX technique was used to screen the aptamers of living cells of Escherichia coli.It is investigated of the preparation of single-stranded DNA,the detection of nucleic acid library for each round of screening,and the cloning of aptamers of nucleic acid.Single stranded DNA was successfully prepared in the screening process,and the aptamer library was monitored in each cycle of the selection to ensure the quantity of the screening.The aptamers was amplified and cloned to obtain the nucleic acid sequence targeted to Escherichia coli.This will facilitate the establishment of a new method for microbial detection based on nucleic acid aptamers.