The P2P streaming system must have the adaptation ability to the heterogeneity of the peer nodes and networks. An adaptive scheme on video streaming over multi-hop path in P2P networks is proposed. The streaming server probes the network parameters in the multi-hop path periodically, and adjusts the output bitrate and the encoding structure according to the probing result. The intermediate peer nodes elegantly discard some frames to adapt the output rate to the bandwidth while alleviating the degradation in the decoding video quality in a delay-constrained way. The experimental results show that the video streaming data can be transferred in the multi-hop path efficiently and adaptively by the proposed scheme.