The invention discloses an Internet-based video-audio transmission system and a video-audio stream distribution method thereof. The system comprises a front-end subsystem, a client subsystem, and a central service platform; besides, the central service platform includes a client application server, a service management subsystem, an alarm service subsystem, an authentication, authorization, accounting (AAA) server, a platform management subsystem, a scheduling subsystem, a storage subsystem, a distribution subsystem, a control service subsystem, and a front-end application server. In addition, the invention also discloses a video-audio stream distribution method of the Internet-based video-audio transmission system. The scheduling subsystem carries out reasonable scheduling on videos and audios of the distribution subsystem according to a current using situation of the system; and the distribution subsystem sends video and audio streams to a client terminal having demand; according to scheduling information of the scheduling subsystem. According to the invention, the system and the method thereof have the following advantages: simultaneous access to and use of a same video-audio stream by multiple users is supported; it is convenient to manage the system; and the application range is wide, and so on.