ASHP (Air Source Heat Pump) is a kind of efficient air-conditioning technology which can take air as heat or cold source and provide hot water or chilled water for a floor radiant system. On the other hand, recent years, as a new type of air-conditioning terminal, floor radiant system has got more and more widely used due to its high thermal comfort and low energy consumption. In this paper, based on an office building in Shanghai, the operation of a floor radiant system combined with ASHP in heating mode is analyzed in order to study the actual effect of this system. Besides, it is also compared with the operation of a FCU (fan coil unit) system combined with ASHP for the purpose of investigating the influence of different heating thermals on the performance of the air-conditioning system. The results show that floor radiant system can provide a more comfortable and more stable indoor thermal environment, while it consumes less energy than FCU system.