Abstract: Trailers are the most widely used method of movie advertising, with the purpose of building consumer awareness and expectations before the release of the movie. In the past, movie trailers were shown at the cinema or on television. Nowadays, trailers appear on the video websites. The effects of online pre-launch movie trailers include two periods:before the release of the movie and after the release of the movie. In the paper, the effects of movie trailers on the viewers' awareness and preference and the effects of the viewers' awareness and preference on the movies' box office revenue are studied. Based on the theories of pure exposure and consumer engagement, the research hypothesis is put forward. Data is collected from mtime.com(www.mtime.com) and entgroup.com(www.entgroup.cn) and text sentiment analysis methods are used to extract the sentiment words from the viewer comments of the movie trailers. A hurdle model is established to examine the effects of movie trailers on the viewers' awareness and preference. A cross section data model and a panel data model are established to examine the effects of the viewers' awareness and preference on the openingweek box office revenue and the weekly box office revenue. The results show that:(1) the release time, the number and the length of movie trailers have effects on the number of the viewer comments.(2) The number of viewer comments and the frequencies of sentiment words have effects on the box office revenue.(3)Before the release of the movie, the frequencies of the words about "joy" and "sadness" have effects on the box office revenue. After the release of the movie, the frequencies of the words about "like" and "dislike" have effects on the box office revenue. The conclusions of the study can provide support for movie marketing strategy development and marketing resource allocation.

Key words: movie trailers, online pre-launch, awareness, sentiment, box office revenue