The Institute of High Energy Physics (IHEP, China) is the biggest and comprehensive fundamental research center in China. Accelerator Division (AD) conducts research on accelerator theory, technology and its applications, which include RF, microwave, power, ultrahigh vacuum, precision machinery, auto-control, beam diagnosis, low temperature superconductivity, and radiation shielding. The AD has accomplished construction and operation of the BEPC and its upgrade BEPCII, is undertaking design and construction of the China Spallation Neutron Source (CSNS) and China Accelerator Driven subcritical system (China-ADS). The R&D activities in AD will be presented.