Social Network Service(SNS) is widely used these days and many people tend to communicate with each other on SNS. Therefore, it can be expected that when communicating on Twitter, people use different politeness strategies related to ‘face’ in different contexts. This paper aims to analyze what type of politeness strategies are used in English Twitter threads. Two American politician Twitter feeds were chosen for the research and 411 tweets were analyzed in terms of tweet context and the tweets were divided into five categories. In each category, each tweet was analyzed based on Brown & Levinson(1987)`s politeness strategies. The highest tweet messages are in regard to praise and expressing support and opposing and criticising was next. The results show that people used the positive politeness strategy more when praising and expressing support. On the other hand, the negative politeness strategy was the highest strategy in opposing and criticising categories. From the research, the results shows that it is difficult to engage in Face Threatening Acts(FTA) even though people have relative anonymity when communicating on-line through SNS.