Objective The study and memory function changes with the growth and senescence course in brain. The study of substance basis for this changes is the hotspot in neuroscience research at present. It' s very important for improving the brainpower in child and protecting intellect decline in elder. The ability of study & memory and the expression of cortex neurofilament protein, which is a kind of framework protein in rats at different ages were analyzed in this paper. Method SD male rats were choice in this study, the rats were divided into 22 days, 1 month, 5 months, 10months and 24 months age groups. The ability of study and memory was evaluated by channel water maze. The neurofilament protein expression in parietal and frontal section in rats was quantificationally measured by immunohistochemistry and image analysis. Results The swimming time and error count in immature rats (age 22 days and 1 month) and old rats (age 24 months) were longer and more than adult rats (age 5 months and 10 months), the difference is significant(P＜ 0.05). This means that the study and memory function in immature and old rats were lower than adult rats. The highest expression of neurofilament protein was in 10 months age group, next is 5 months group, 24 months group, 1 month group in turn. The lowest was 22 days group. It ' s significant in different groups. The study and memory function is positive correlation with expression of neurofilament protein(table 1 ). Discussion The nerves mechanism of study and memory depend on the plasticity of nerves system in one aspect, on the other hand, it also depends on the integrality of nerve net. There are parallel processing and complementation features in nerves system. The transmit of a sign are parallel by many nerve fiber. The impediment of one axon can' t interrupt the whole pathway, but the quality of massage transport is affected. Thus, if the development of nerve transport pathway is better, the mount of message is greater, it is more benefit to study and memory. Neurofilament protein is a kind of framework protein in neuron; it is the basic component in nerve net. This study shows that the expression of neurofilament protein become more and more strong with animal growth (22 days, 1 months, 5 months and 10 months), that means nerve net becomes more integrality. But in the 24 months aged group, the expression of neurofilament protein declines, indicating nerve net begins degeneration with senescence.At the same time, the study and memory function changes similarly. Statistics analysis shows that the study and memory function is positive correlation with expression of neurofilament protein, correlation coefficient is 0. 735. This argues that perfect nerve net is the base of study and memory function, and the expression intension of neurofilament protein is its indication.