The invention provides a transmission path selection method and device. The method comprises the following steps: a first device in a network transmits a probe packet including a routing factor, a first probe parameter and a quintuple to a section between the first device and a second device or to all transmission paths; and the first device, according to a probe responding packet fed back by the second device, selects a routing factor of a transmission path with comparatively light load as the routing factor of a data packet to be transmitted. The method can always prevent data from being transmitted through the transmission path with heavy load, so that the problem of data congestion in the network is eliminated.