Recently, organization downsizing has become the major means used by corporations to seek survival or better growth. Organization downsizing has some purposes: to reduce the cost of personal, to get better efficiency, to rearrange the deployment of human resource after M&A. Besides those economic purposes, some scholar think corporations do organization downsizing to get legitimacy. Generally speaking, the purpose of organization downsizing is to get better efficiency or the legitimacy. But lots of researches indicate lots of organization downsizing can not achieve expected goals. Although some corporations can achieve the goal of organization downsizing, many corporations can¡¦t achieve expected goals, and there are also some corporations do a lot of organization downsizing but their situations go from bed to worse. Among the researches of why organization downsizing can¡¦t achieve expected goals, many researches indicate that the application of organization downsizing will make huge negative impact to survivors. Some scholars call that impact survivor syndrome. Besides, some scholars investigate the reason of the failure of organization downsizing from the point of informal social network. Because the theory of social capital includes trust, organization involvement, social network and so on, we can more understand the reason of the failure of organization downsizing from the point of social capital. So the purpose of this research is to use the theory of social capital to investigate the impact of organization downsizing and provide some advices to corporations, so that they can do better about organization downsizing. This research uses case study to understand the reason and the process of organization downsizing, and investigates the negative impact of organization downsizing. Survivor syndrome and social capital play important roles in the analysis of the failure of organization downsizing. This research finds that organization downsizing will do huge damage to social capital. If corporation don¡¦t understand the importance and benefit of social network, then the application of organization downsizing will hurt social network and corporations can¡¦t achieve expected goals. Besides, in the analysis of case study this research finds that organization downsizing also hurt trust, involvement, incentives to cooperation and so on, these issues are part of survivor syndrome, but we also can use social capital to explain.