We focus on modeling and computing of aware context with uncertainty for making dynamic decision during seamless mobile service. We re-examine formalism of random set,which is not finite-set statistics (FISST), argue the limitations of the direct numerical approaches, give new modeling mode based on random sets theory (RST) for aware context, and propose our computing approach of modeled aware context. In addition,we extend classic D-S evidence theory after considering reliability, time efficiency, relativity of context, and compare these two kinds of relative computing methods for uncertain context.By comparing, the validity of new context-aware computing approach based on improved random set theory (IRST) or extended D-S evidence theory (EDS) for proactive service has been tested.