The invention discloses a method and device for data transmission. The method includes the steps of: detecting a data transmission request sent by a client to a target server; when the data transmission request sent by the client to the target server is detected, judging whether a transit server is started, the transmission rate of the transit server being higher than that of the target server; and if that the transit server is started is judged, sending the data transmission request to the target server through the transit server. The method solves the technical problem in the prior art that an acceleration effect is relatively poor in a data transmission process.