A multimedia data streaming system and a method thereof transmit multimedia data to a receiver by a streaming server through a dynamic streaming process. The multimedia data streaming system includes a converting module and a scheduler module. The scheduler module is used to obtain the bandwidth condition between the streaming server and the receiver dynamically. The scheduler module can request the converting module to convert the original data into streaming pieces with the optimal bit rates in accordance with the bandwidth condition detected. The streaming pieces can be transmitted to the receiver by the streaming server.