Objective Using a chronic unpredictable stress animal model to study the changes of the learning and memory of mice and effects of L-tyrosine interference were observed.Methods To create a chronic unpredictable stress animal model,spontaneous actions test and Morris water maze test were be used to study the changes of the learning and memory of mice.And at last,the content measurements of NE,DA in brain were employed to further estimate the impairment of stress and the effect of drug interference.Results Spontaneous actions induced by chronic unpredictable stress were remarkably reduced[(1.36±0.43)m vs (2.01±0.31 )m,P<0.01] and being supplied with L-tyrosine [(1.93±0.37) m vs (1.36±0.43) m,P<0.01],and morris water maze test showed that the period of the stress group(62.4±25)s had been gradually delayed(P<0.05).With the supplement of L-tyrosine,it had got an elevation (P<0.05 ,respectively).The contents of DA in pallium,hippocampi and hypothalamus of the mice submitted to stress alone were significantly decreased (respectively,P<0.01,P<0.01,P<0.05) and so were the level of NE(P<0.01) except of hippocampi,both of which would be reversed with the supplement of L-tyrosine.Conclusion Chronic Stress could change the behaviors of mice observably and the contents of DA,NE in pallium,hippocampi and hypothalamus. Key words: Chronic Stress; Morris water maze test; Behave; L- tyrosine