Library blog is one of the tools to help library development. In order to understand the main characteristics and influencing factors of blogs, there are 71 library-related blogs build by 42 university libraries surveyed. Applies principal component and cluster analysis methods and have the following conclusions: 1.University Libraries almost build the blog by themselves. 2.The subject of university Library blogs usually is about the selected collections. 3.Long-term operation of blog has high traffic and visibility. 4.University Library blog can be divided into 3 to4 clusters. 5.University Library blog is still growing and changing.