The invention discloses a method for adjusting a sending rate in a bandwidth detection stage and a congestion control algorithm, and the method comprises the steps: firstly increasing the sending ratethrough a speed increasing factor g in a first RTT in the bandwidth detection stage, and then sending a round of data package, so as to carry out the bandwidth detection; judging the congestion condition of the current network according to whether ACK packets of all data packets sent in the round are received within a certain period of time; when the condition of the current network is good, adjusting the acceleration factor of the sending rate according to the current round-trip delay and the historical maximum transmission rate; when the condition of the current network is poor, reducing the sending rate to send a round of data packets, i.e., reducing the sending rate to empty the queue in the second RTT of the bandwidth detection stage; and in the remaining period of the bandwidth detection stage, determining the sending rate according to the real-time transmission rate. The method can give consideration to the transmission efficiency, convergence and fairness.