Wenchuan Earthquake,8.0 Richter Magnitude, is themostdestructive,mostwidely-spread and the one entails themostdifficulties in disaster-relief since the founding ofPeoples Republic of China.Alongwith the earthquake,many secondary disasters, such asmountain collapses, landslides and debris flows and dammed lakes occurred and enlarged the disaster.After the earthquake,NationalDisasterReduction Committee(NDRC)and Ministry ofCivilAffairs(MCA) trig-gered the domestic and international satellite remote sensing data achieving mechanism mi mediately, including the Interna-tional CHARTER Space and MajorDisasters.The achieved datawere used for the continuous disastermonitoring and urgentdisaster assessment, and provided effective information in disaster relie.f This paper establishes an urgentassessmentmethod for catastrophe, which is based on the interpretatingwith remote sensing data and the deducting by spatial analysis. Taking the urgent assessment using remote sensing data during the Wenchuan Earthquake as an example, this paper apply themethod into the assessment for the 152 counties ofSichuan,Shanxi andGansu provinces. The results show thatbuildings are destroyed seriously, and the affected population distribute in a verywide area. In genera,l the disaster loss isdistributed corresponding to the faultzone. The disaster loss inmoun-tain area is larger than that in plain area, and the damage in village area ismore serious than that in urban area. Wen-chuan, Beichuan, Qingchuan, andMianzhu and other 8 counties in Sichuan province are the most seriously damaged counties. Wen County in Gansu province andMian county in Shan xi province are serious damaged. By validation with field investigation, the efficiency of the assessmentwas approved. The paperdevelopes a step-by-step collectionmethod of assessment, which takes the advantage of the remote sensing data andmeets the efficiency need ofurgentdisaster assessment. Themethod is also useful for the coordinative operation and comprehensive assessment. Themethod is scientific,applicable, and feasible in disaster assessmentwith remote sensing data during catastrophe.