Abstract: Beijing Theater is a multi-purpose auditorium mainly for play performance,with a capacity of 1,000 seats.To meet the acoustic requirements of different kinds of performances adjustable sound absorption structures are installe in the hall.Emphasis has been placed on the sound diffusion for gratifying natural sound effect of music performance.In addition,an orchestra shell and lifting orchestra pit have been also employed.The acoustic design of the Theater and the success achieved are discussed in this paper to testify the necessity and possibility of multi-purpose utilization in acoustics in an auditorium.