The national standard《Post-earthquake field works Part 4: Assessment of direct loss》 (GB 18208.4-2005) has been playing an important role in earthquake loss assessment, relief organization and homeland rehabilitation since it was issued in 2005 in China. The earthquake losses assessed are much less than other natural disasters (such as floods, drought) or foreign earthquake losses. How to assess seismic economic loss reasonably has been a key issue domestic seismic workers concern. In this paper, an earthquake-induced building decoration loss assessment method for urban zones is presented firstly. Then, based on statistical analysis of collected more than 600 pieces of cost data and 30 pieces of expert questionnaires, the distribution proportion of moderate–and–high–grade decoration building, the proportion of decoration cost and total structure cost, the loss ratio of decoration damage in small, Medium and big cities are given, respectively. The correction coefficients are also given depending on different economic development and use. Finally, its practical application in Sichuan Wenchuan Ms8.0 great earthquake loss assessment is introduced. Thus, some references and basis for further modifying and perfecting earthquake loss assessment standard in China are provided.