A method for transmitting video data, comprising: sending (101, 202), by a first game client, a first log-on and connection establish request respectively to a relay server and a Peer to Peer, P2P, server, wherein the relay server and the P2P server are provided by a video network game system; sending (101, 202), by a second game client, a second log-on and connection establish request respectively to the relay server and the P2P server; forwarding and transmitting the video data, by the first game client and the second game client via the relay server, when a first relay connection between the first game client and the relay server is established successfully and a second relay connection between the second game client and the relay server is established successfully; suspending, by the first game client and the second game client, the forwarding and transmitting of the video data via the relay server, when a first P2P connection between the first game client and the P2P sever is established successfully and a second P2P connection between the second game client and the P2P server is established successfully, after transmission of a first frame of data between the first game client and the second game client is completed with a P2P mode; transmitting (104, 204), by the first game client and the second game client, directly the video data with the P2P mode; characterized by, during the process of transmitting the video data by the first game client and the second game client with the P2P mode, when packet loss of the video data transmitted between the first game client and the second game client is larger than a predetermined coefficient, continuously transmitting, by the first game client and the second game client, the video data via the relay server; and sending, by the first game client, the first log-on and connection establish request to the P2P server; sending, by the second game client, the second log-on and connection establish request to the P2P server; when the P2P server restores, respectively receiving, by the first game client and the second game client, a P2P connection success response sent by the P2P server, suspending transmitting of the video data via the relay server, and transmitting the video data with the P2P mode (206, 207). sending (101, 202), by a first game client, a first log-on and connection establish request respectively to a relay server and a Peer to Peer, P2P, server, wherein the relay server and the P2P server are provided by a video network game system; sending (101, 202), by a second game client, a second log-on and connection establish request respectively to the relay server and the P2P server; forwarding and transmitting the video data, by the first game client and the second game client via the relay server, when a first relay connection between the first game client and the relay server is established successfully and a second relay connection between the second game client and the relay server is established successfully; suspending, by the first game client and the second game client, the forwarding and transmitting of the video data via the relay server, when a first P2P connection between the first game client and the P2P sever is established successfully and a second P2P connection between the second game client and the P2P server is established successfully, after transmission of a first frame of data between the first game client and the second game client is completed with a P2P mode; transmitting (104, 204), by the first game client and the second game client, directly the video data with the P2P mode; characterized by, during the process of transmitting the video data by the first game client and the second game client with the P2P mode, when packet loss of the video data transmitted between the first game client and the second game client is larger than a predetermined coefficient, continuously transmitting, by the first game client and the second game client, the video data via the relay server; and sending, by the first game client, the first log-on and connection establish request to the P2P server; sending, by the second game client, the second log-on and connection establish request to the P2P server; when the P2P server restores, respectively receiving, by the first game client and the second game client, a P2P connection success response sent by the P2P server, suspending transmitting of the video data via the relay server, and transmitting the video data with the P2P mode (206, 207).