Abstract: Since Caenorhabditis elegans lives in a complex ecosystem,it has evolved the power to perceive and response to a variety of environmental stimuli effectively.Besides the usual abiotic and biological stress,such as unsuitable odors,high or low temperatures,hyperhaline stimulation and so on,infection of pathogenic bacteria can also induce the behavior of avoidance in C. elegans.The avoidance triggered by pathogens helps the worms distinguish the harmful bacteria from the food bacteria and escape from the fatal dangers quickly,which hence enhances the possibilities of C. elegansto survive.It has been reported that the bacterial pathogens,at least including Pseudomonasaeruginosa PA14,Serentia marcescens and Bacillus thuringiensis,can induce the avoidance.Furthermore,the aversive behavior is mainly divided into two categories based on the different mechanisms:an instinctive escape response and the avoidance depending on learning.In this paper,the related signaling pathways involved in those two types of avoidance were both reviewed.