The invention discloses a multimedia synchronous play method, device and system, and a terminal. The method comprises the steps of detecting currently cached data volume of a cache space in a process of synchronously playing multimedia data of the cache space; detecting a current data caching rate; and controlling the cached data volume of the cache space to be kept between a second preset threshold value and a third preset threshold value according to the currently cached data volume and the current data caching rate. Cache management is carried out on the media data in a constant current approximate mode, when multiple play devices cache the data, the bandwidth is employed reasonably in balance, the bandwidth occupation will not be increased explosively, the intermittent sudden change fluctuation is avoided, the network pressure is reduced, the synchronism of the cached data is ensured, and synchronous play of the multiple play devices is realized.