Objective To generate the interleukin 34 ( IL34 ) transgenic mice and investigate its functions on mouse＇s immune system． Method The transgenic plasmid was constructed by inserting the human IL34 gene in the downstream of CMV promoter． The transgenic mice were produced by microinjection method and the genotype was detected by PCR． The expression level of the protein was determined with Western blotting． The pathologic changes of important organs were observed by histochemical stain． Result Two lines of transgenic C57BL /6J mouse of IL34 gene were established． The expression levels of the IL34 gene was higher than the endogenous IL34 in the spleen tissue． Histology analysis demonstrated the important organs of the IL34 transgenic mice such as brain，heart，liver，kidney，intestine et al were nomal except spleen． Compare with the wild type mice，the germinal center of spleen was more activity，the area of white pulp were larger． Conclusion The IL34 transgenic mice were established successfully． Over-expression of IL34 in the immune systerm needs further investigating