Abstract: An acoustical reflecting shell must be installed on stage, when a symphony, chamber music or choral music performs in theatre. Acoustical reflecting shell is one of the most important facilities for multi-functional theatre. It helps to reflect sound to audience area, improve sound quality of auditoriums and interaction between the band members. This paper mainly describes the application examples and acoustical measurement results. The acoustical reflecting shell on stage significantly reduced the coupling effect between stage space and audience hall, thereby increased the reverberation time of audience hall except that of the low frequency part. A multi-purpose theatre with a reflecting shell on its stage fails to make a sound quality as good as that in a concert hall. By installing a cover on the stage, the clarity of audience hall decreases, while the sound strength is greatly improved.