[en] Towards the future CMS RPC upgrade, a real-size mosaic high-rate MRPC has been designed and developed by Tsinghua University. The prototype is a 5-gap counter composed of the low-resistive glass. Because the maximum size of this glass cannot exceed 330 × 280 mm², 6 regions of glass stacks are mosaicked together in order to achieve a large active area. This prototype was tested in HZDR-ELBE with 30 MeV e-beam. It shows an efficiency above 95% at the rate of 2 kHz/cm². The time resolution is around 55 ps, and the cluster size is below 1.5. The performance is almost unaffected by increasing the rate to 11 kHz/cm². This design is proved to be fully capable of the CMS upgrade requirement by this HZDR beam test. The mosaic technology will make the high-rate MRPC a good choice in large-area timing systems.