We initiated the disaster assessment of Lushan M_s 7.0 earthquake immediately after the shocking. The disaster situations including the ratio and distribution of affected population, the ratio of damaged houses, the distribution of casualties and the damaged roads were estimated for four times after seismic intensity was mapped. The whole assessment procedure, referring to the availability of data, was developed from qualitative assessment to quantitative assessment. As compared to the announced data from the Ministry of Civil Affairs, the accuracy of rapid assessment on affected population was 95%, that of damaged houses was 73.3%. The assessment system, including the models, methods and softwares, was validated to be practical after the successful assessment of Yushu earthquake, 2010. In addition, The problems existed in the assessment were rethought, and the solution and direction of the earthquake situations assessment were also put forward.