Artificial genetic parts should be modularized and can be predictably scaled up via assembly or reused in other contexts. Under intracellular physiological conditions, however, the functions of the assembled parts are severely impeded by multi-level physiological interference, i.e., most artificial assembled systems cannot be functional as predicted. Here we proposed a concept of synthetic physiology, defining it as the branch of synthetic biology to investigate and control interferences between artificial genetic parts and intracellular physiological system. Under such framework, we describe the part-host interactions and review the methods and strategies used to characterize and address these interactions.