According to the theory of steady heat flow balance, adopting the method of theoretical analysis and numerical iteration, a steady heat transfer model of double hollow glass considering long wave radiation transmittance of glass and indoor and outdoor space coupling condition was established. Based on the model, overall heat flux, overall heat transfer coefficient, effective long wave radiation transmission coefficient, radiation heat transfer coefficient of inside and outside surfaces were calculated and analyzed under classic indoor and outdoor air temperatures in winter and geometry boundary conditions of indoor and outdoor environments to double hollow glass composed of ordinary clear glass sheets. The results show that if long wave radiation transmittance of every glass sheet is 01, effective long wave radiation transmission coefficient of double hollow glass will approach to 01670177; comparing to the situation ignoring long wave radiation transmittance of glass, radiation heat transfer coefficient of inside surface of double hollow glass increases about 25%, and radiation heat transfer coefficient of outside surface increases over 1.0 times in classic outdoor air temperature condition(-400℃). So the adverse effects of the long wave radiation transparent of glass on energy saving capability of double hollow glass are obvious, and long wave radiation transmittance of glass cannot be ignored in energy saving design and calculation. Furthermore, with decreasing air temperature difference between indoor and outdoor environments in winter, overall heat flux of double hollow glass decreases gradually, however, overall heat transfer coefficient and radiation heat transfer coefficients of inside surface and outside surface of double hollow glass increase gradually.