The inner emotional activities of the characters in the film mainly refer to the rich and subtle emotional state, or the personality psychological changes with strong color, which are displayed in the process of plot development or in specific circumstances. But the inner activities of the characters are secret, which is difficult to understand and perceive before the formation of perceptible symbols. The image is good at narration, but not good at the simulation of inner emotional movement. Therefore, the director uses vocal music to reveal the specific emotions and unique emotional and psychological activities of specific characters. Moreover, with the development of the plot and picture, vocal music can well express the characters' unique emotional experience, and help the audience deepen their understanding and influence of emotion. The vocal music in many movies plays an important role in rendering and strengthening emotional strength