The conventional calculation of building indoor moisture load of always omits the effect of interior moisture release of envelope. However, its effect especially that of new-completely energy-saving building is very large. The paper, which took the new-built building in Harbin as an example, analyzed the effect of heat and mass coupled transfer envelope on modeled room moisture load in cold serious areas. The moisture load modeled results of multilayer envelopes with different setting were contrasted in the first four years use. The result showed that, for a new-built building, the using of vapor retarder on interior of insulation layer or glazed brick on exterior of envelope would increase the moisture load, which would be reduced if defer the time for plastering glazed brick.