In today's workplace, it is a social trend for workers to have a variety of evolving real-time communication software to help them communicate and coordinate at work. The Instant Messaging (IM) software LINE has played an important role in the trend of responding to the real-time needs of the public to improve government effectiveness. However, because of its immediacy and convenience, government workers often receive a high volume of messages. There is a lack of relevant and objective research data on the impact on civil servants’ perceived experiences of their work under such a workplace norm as a basis for promoting the use of LINE in the government sector. To address this gap, this study examined the relationship between online social anxiety, Line cognitive fatigue (LCF), perceived information overload of instant messaging (PIOIM), and job engagement among civil servants based on the media richness theory.