The invention discloses a path estimating method which comprises the steps of: calculating a path quality estimating parameter according to a round-trip-delay, a packet loss probability and a congestion window of a path; dividing the path into an available path and an unavailable path according to the path quality estimating parameter; transmitting data on the available path and calculating the round-trip-delay, the packet loss probability and the congestion window of the path in a process of transmitting the data; and sending a heartbeat message in the unavailable path for calculating the round-trip-delay, the packet loss probability and the congestion window of the path. According to the invention, the path quality can be detected in real time, the path quality can be accurately calculated according to the simple parameter and the data transmission path is regulated and selected in real time, therefore the quality of the data transmission path is ensured, and the data is reliably transmitted. The path quality can be effectively estimated, and the transmission quality of streaming media data is improved.