Open-plan administrative offices (OAOs) and open-plan research offices (OROs) are two common types of open-plan offices in the modern city, in which occupants' daily task and work pattern are quite different from each other. In this paper, a comparative field study is conducted between OAOs and OROs, aiming to better understanding the effects of IEQ in these two types of offices. Both physical measurement and subjective evaluation results that relate to the key IEQ aspects (layout, air quality, thermal comfort, lighting and acoustic environment) are compared and analyzed, which are collected from 13 OAOs and 12 OROs in China. The results demonstrate again the high correlation between office IEQ and work productivity, and suggest that acoustic environment and air quality should be paid special attention to in the surveyed offices. Moreover, although the physical conditions of personal space (8.86 m2) and temperature (26.56 °C) in OAOs are significantly better than those in OROs (4.53 m2 and 27.53 °C, respectively), no significant differences are found between OAOs and OROs in subjective evaluation results of either personal space or temperature. In addition, the physical acoustic environment in OROs (LA,eq = 46.7 dB) is significantly better than in OAOs (LA,eq = 51.9 dB), however, occupants' satisfaction level of acoustic environment for OROs is significantly lower than for OAOs. These findings reveal occupants' perception and IEQ demands can be different in OAOs and OROs. OAO occupants tend to require larger personal space than occupants in OROs, while people working in OROs can endure higher temperature and have higher requirements for acoustic environment.