The modular high-temperature gas-cooled reactor (MHTGR) is one candidate for the fourth generation nuclear energy system technology. It has distinct advantages in terms of inherent safety, economics potential, high efficiency, potential usage for hydrogen production, etc. It is very attractive and competitive in the world, and has a broad development prospects. With the success of 10 MW high-temperature gas-cooled reactor (HTR-10), constructed by Institute of Nuclear and New Energy Technology (INET) of Tsinghua University of China, a larger commercial MHTGR nuclear power plant, namely the HTR-PM, is proposed. At the same time, another plan for higher efficiency, namely the HTR-10GT (direct gas-turbine), is also proposed to study. However, the bearing technology used in the primary loop is becoming an important problem because of the special environment of the reactor. Active magnetic bearing (AMB) is replacing mechanical bearing as the perfect sustaining assembly for the primary loop because they have several advantages: they are free of contact, do not require lubrication, are not subject to the contamination of wear, have endurance, and control performance very well. But there is no successful precedent for nuclear power station in the world. AMB's practicality, reliability, stability and so on are all needed to study by theory and experiment. INET are engaged in these research works and experiments. These works will be introduced and summarized in this paper. It offers the important base for AMB applied in the modular high-temperature gas-cooled reactor. (C) 2014 Elsevier Ltd. All rights reserved.