This thesis attempts to analyze the changing trend of Sina-Weibo, the leader of microblog services in China by investigating the content and disseminating pattern of the top-ranking grassroots Weibo account Choice Selection of Cold Jokes (冷笑話精 選, CSCJ) in grass-roots micro-blogs. The inquiry first analyzes the content of CSCJ in two periods, 2009-10-23 to 2010.1.23 and 2011-11-19 to 2012-2-19, to illustrate a clear profile of its structure and situation of variation in different aspects. Moreover, this study also investigates the pattern of reposting in the CSCJ using a specific visual tool to trace the path of some selected posts’ retweet situation. According to the finding of this research, it indicates that the changing trend of grassroots accounts in Sina-Weibo seems to be a process of commercialization. The great powers control enormous accounts in Sina-Weibo for the purpose of business promotion. After an account was established with enormous number of fans, it develops into a commercial account used for reposting advertising and promotion information. However, the original space for grassroots creativity in exchanging jokes, criticizing society and performing entertainment on the Internet by ordinary netizens has been eroded or even controlled by the commercial capital. Specifically, it finds that CSCJ just uses “cold joke” as a gimmick to build its name and attract more fans at the beginning. After becoming popular in Sina-Weibo, it changes into a business cabinet, or we can say a brand Weibo account, for diversified goods, no matter jokes or non-jokes, its own products or others’. Moreover, it also offers a place for marketing to some extent. The most noteworthy is the pushing posts. It just likes a 4 hotbed of viral marketing, which motivating the action of reposting of the original post of CSCJ and the posts with a pushing element can increase the opportunity of reposting. By analyzing the pattern of reposting through the visual tool analysis, the study also notices that there are sometimes small satellites besides the main center of CSCJ’s posts. These small satellites suggest the existence of influencers in marketing of Sina-Weibo. Additionally, there exit embedded-advertising although the proportion of it is not high. Last but not least, through studying the pattern of information dissemination in CSCJ, it dovetails nicely with the model of fission dissemination of the social media.