Online lottery promotion during holidays has become an important approach for online communities to attract new users and activate current members. The objective of this study is to empirically examine the influence of an online lottery promotional campaign on user acquisition and user engagement from both short-term and long-term perspectives. The aquired data recorded individual users' daily activities on the mobile application before, during and after the lottery promotional campaign, as well as users' participation in the lottery draw and the awards received. This study found that the online promotion attracted more users to register, activated the registered users during the lottery promotion and the users who won non-virtual prize (monetary prize) will be more active in commenting after the promotion. While in the long run all the users' posting activities slightly decreased after the promotion, the lottery promotional campaign is effective in attracting and activating users in short term period.