The ideas of smart home and home automation have been proposed for many years. However, when discussing future homes, related researches usually focus on deploying many smart appliances (or devices) within a home environment and executing those appliances by pre-defined automation mechanisms. Moreover, users usually think semantically in their home domains, such as "I want to turn off all the lights at the second floor". If a home automation system cannot operate semantically, it is difficult to be used in real home environments. This paper proposes an user-modifiable semantic home automation framework (USHAF), which adopts Web Service and WSBPEL for automated process execution, and OWL as well as OWL-S for home environment definition. Finally, the proposed system is compared with other related systems.