The calculated formula of SEER in JRA4046-1999 and GB7725 was analyzed and modified for convenient use. The map of Chinese temperature-strip was given and the weather data for eight cities near 30 years were selected. On the basis of these weather data and the temperature-strip in GB7725
the regional SEER of frequency conversion room air conditioner was calculated in the different regions. It is concluded that the regional SEER is an important parameter for frequency conversion room air conditioner. Some measurements were suggested to improve the energy efficiency ratio for energy saving and the whole seasonal energy efficiency ratio.