To solve matching problem between the sun′s available heat and heating demand in the design of passive solar building. The indicator of “solar passive heating thermal coefficient”(SPHTC) was proposed based on the principle of unsteady heat transfer. Based on case study of Lhasa and Beijing, the contribution of solar radiation for heating energy consumption was analyzed by calculating SPHTC. The control strategy for intermittent active and passive combined solar heating system was proposed, and the feasibility of such system in regions with rich solar energy was evaluated .