Method and device for adjusting bit rate in video calling based on VoLTE, and mobile terminal are provided. The method includes: determining whether the data receiver transmits a TMMBR packet for the first time or has received a TMMBN packet from a data transmitter, or whether the number of times a same TMMBR packet has been retransmitted exceeds a predetermined time; if yes, estimating downlink reception bit rate and calculating downlink packet loss rate of RTP packet; calculating transmission bit rate of the data transmitter which is requested by the data receiver based on the estimated downlink reception bit rate and the calculated downlink packet loss rate of RTP packet; and transmitting the TMMBR packet to the data transmitter based on the transmission bit rate of the data transmitter. A bit rate can be dynamically adjusted based on actual network bandwidth, which may improve quality of video calling.