Abstract: Nuclear criticality safety is a peculiar kind of safety issues in nuclear science and industry, and is a special safety problem throughout the whole nuclear fuel cycle and the lifeline of the developments in nuclear energy. Nuclear criticality safety technology is a research field for preventing unexpected neutron chain fission reactions which would cause radioactivity release accident in nuclear science and industry. The research of nuclear criticality safety technology in China originated and developed in China Institute of Atomic Energy (CIAE). Based on CIAE, China National Nuclear Corporation set up the Nuclear Criticality Safety Center. The technology R&D system nowadays becomes comprehensive after long-term accumulations and developments. The progress in the research of nuclear criticality safety technology will be briefly introduced with the topics of critical experiment, criticality monitoring, theoretical analysis and information technology in the paper.