To accurately size up the international communications effect of Chinese and foreign media on overseas social networks，this paper evaluates the effect of communications on three major overseas social networks：Twitter，Facebook and YouTube，in three stages. One is a year’s communications by eight Chinese mainstream media accounts；another is the horizontal comparison between the Chinese media and 40 well-known foreign media accounts；and the other is an in-depth analysis of the hot posts，hot videos，hot words and hashtags. Based on the evaluation results，the paper tries to put forward some well-targeted proposals for Chinese media in their communications activities on overseas social network platforms.