With the development of magnetic confinement fusion research, higher magnetic fields are needed. Commonly used is Nb3Sn superconductor in high-field magnets, which does not have much potential for improvement. It is necessary to develop new conductor with new superconducting materials. Bi2Sr2CaCu2Ox is such a promising material. One sub-size conductor with 42 wires has been designed and manufactured at Institute of Plasma Physics Chinese Academy of Sciences (ASIPP) and its ac loss has been tested in the standard magnetization magnet for transverse magnetic fields at the University of Twente. The phenomenological model was used to analyze the test results. And the results showing that the coupling loss of Bi-2212 conductor is greater than that of Nb3Sn conductor under the same condition. This result may due to the fact that the silver matrix used in the Bi-2212 strands has a lower electrical resistivity than the copper matrix of the Nb3Sn strands.