Secondary salinization in streams is defined as increasing salinity due to the migration and accumulation of exogenous soluble ions. It is generally caused by anthropogenic disturbances,such as agricultural cultivation,degradation of vegetation in a riparian zone,discharge of mining and sewage wastewater. Secondary salinization in streams can be characterized by complexity of ionic composition and the intermittent fluctuation of salt ions. Previous studies have found that secondary salinization in streams affects algae,macroinvertebrate and fish communities structure,i. e. species richness,biomass,diversity and functional feeding groups. Intolerant species stressed by a hyper-salinity environment always have a lower occurrence frequency,e. g.,sensitive macroinvertebrates transfer to a hypo-salinity environment through frequent drift behaviors. Similarly,sensitive fishes disappear from the salt-stressed environments. Tolerant species live in hyper-salinity environments by means of their different strategies,such as the spawning ritual of ovoviviparous which helps to shorten the time in salt-stressed environments,as well the stronger ability of osmotic adjustment which helps to maintain the inner osmotic balance. Current studies have to face some challenges. First,the single ion or mixture of ions shows different effects on aquatic life. Meanwhile,the dominant ion types and concentrations vary with different salinization water bodies; verifying the effects of a single ion or mixture of ions,one by one,is a huge workload. Second,conductivity and rho(TDS) are used to estimate the degree of salinization in general,and the influence on biological toxicity of organic contaminants or heavy metals and interactions with nutrients or suspended solids,which makes it difficult to determine the independent effect of salinization. Therefore,more efforts should be devoted to illustrating the combined effects of secondary salinization with nutrients and metals against the background of global warming,focusing on the tolerance characteristics of native aquatic organisms and their osmoregulation mechanisms,and validating the optimum salinity ranges of aquatic life obtained from field investigation with those obtained from laboratory tests. In order to protect the health of aquatic organisms,we should develop monitoring parameters which sensitively indicate stream salinization and derive their thresholds.