A method for transmitting data stream includes the steps of analyzing a request to generate a transmitting command, calculating a data receiving ability of a receiving end when receiving the transferring command, calculating an I frame dividing rate, a P frame dividing rate, and a B frame dividing rate based on the data receiving ability, dividing an I frame, a P frame, and a B frame based on the I frame dividing rate, the P frame dividing rate, and the B frame dividing rate to generate a plurality of I frame segments, P frame segments, and B frame segments, transmitting the I frame segments, P frame segments, and B frame segments of the data stream to the receiving end in turn base on the data receiving ability.