A method for calculating bandwidth of UDP-based streaming media network transmission, which is applicable to a server, characterized in that the method comprises: dividing video frame data to be sent into a plurality of sub-video frame data units, and encapsulating each sub-video frame data unit into a sub-video frame packet with a preset sequence number (S101, S201, S301); sending sub-video frame packets with preset sequence numbers to a client, and recording sending start time (S102, S202, S302); receiving a response message sent by the client (S103, S203, S303), wherein the response message is generated based on a sub-video frame packet received by the client, and comprises a first sequence number corresponding to at least one sub-video frame packet that the client requires the server to send and a second sequence number for the received sub-video frame packet; extracting the first sequence number and the second sequence number from the response message, sending a sub-video frame packet corresponding to the first sequence number to the client, and determining whether the client has received all sub-video frame packets of the video frame data based on the second sequence number (S104, S304); recording sending end time of the last sub-video frame packet of the video frame data (S105, S207, S305a), and calculating network bandwidth based on the sending start time, the sending end time and the size of the video frame data (S105, S207), if determining that the client has received all sub-video frame packets of the video frame data, wherein the first sequence number includes: a sequence number of a subsequent sub-video frame packet that the client requires the server to send according to a sequence of sending sub-video frame packets, and a sequence number of the sub-video frame packet that the client wishes the server to send again when network packet loss occurs; and the second sequence number is a sequence number of the sub-video frame packet which is sent by the server and received by the client. dividing video frame data to be sent into a plurality of sub-video frame data units, and encapsulating each sub-video frame data unit into a sub-video frame packet with a preset sequence number (S101, S201, S301); sending sub-video frame packets with preset sequence numbers to a client, and recording sending start time (S102, S202, S302); receiving a response message sent by the client (S103, S203, S303), wherein the response message is generated based on a sub-video frame packet received by the client, and comprises a first sequence number corresponding to at least one sub-video frame packet that the client requires the server to send and a second sequence number for the received sub-video frame packet; extracting the first sequence number and the second sequence number from the response message, sending a sub-video frame packet corresponding to the first sequence number to the client, and determining whether the client has received all sub-video frame packets of the video frame data based on the second sequence number (S104, S304); recording sending end time of the last sub-video frame packet of the video frame data (S105, S207, S305a), and calculating network bandwidth based on the sending start time, the sending end time and the size of the video frame data (S105, S207), if determining that the client has received all sub-video frame packets of the video frame data, wherein the first sequence number includes: a sequence number of a subsequent sub-video frame packet that the client requires the server to send according to a sequence of sending sub-video frame packets, and a sequence number of the sub-video frame packet that the client wishes the server to send again when network packet loss occurs; and the second sequence number is a sequence number of the sub-video frame packet which is sent by the server and received by the client.