Objective：To evaluate the expression and location of the histone deacetylase3（HDAC3） in human placenta with intrahep－atic cholestasis of pregnancy（ICP） and its significance. Methods：Fourty-one women with ICP who delivered from March 2012 to May 2013 in the First Affiliated Hospital of Chongqing Medical University were chosen as the study objects.They were classified into mild group（n=19），severe group（n=22）. Twenty healthy pregnant women who delivered in the same period were chosen as the control group（n=20）. Immunohistochemical was employed to detect the expression and localization of HDAC3 protein in placenta tissue. Western blot analysis was used to quantify HDAC3 protein expression level. Real-time PCR was used to quantify HDAC3 mRNA expression level. Results：（1）The serum levels of tumor necrosis factor-α（TNF-α），total bile acid（TBA），glutamic-oxaloacetic transaminase（ALT） and glutamic-pyruvic transaminase（AST） were significantly higher in severe groups than in mild ICP group and control group（P<0.05）.（2）The HDAC3 protein and mRNA levels in placenta were significantly lower in severe and mild groups than in control group（P<0.05）． （3）The quantitative expression of HDAC3 protein in placenta was negatively correlated with serum TNF-α，TBA，ALT and AST levels. Conclusion：The low expression of HDAC3 may be associated with the pathogenesis of ICP and liver function damage.