Abstract: Based on the structural dynamic theory, the relationship between capacity spectra and lateral load patterns was demonstrated. It was pointed out that different formulae of capacity spectrum curves should be used for different lateral load patterns and the formulas were given. A six-story reinforced concrete frame structure was designed and analyzed using the proposed method, the classical method and the time history analysis method respectively. The result shows that the proposed method is more accurate. Using the proposed method and the different lateral load patterns the seismic response can be bounded within a narrower scope, which will help to know the seismic response more accurately.