目的　以化学计量学为基础，建立一种用于解析平衡态红外光谱数据 的奇异值分解最小二乘法。方法以数值模拟方法构造二组分酸碱平衡体系及其 光谱数据，在 ＭＡＴＬＡＢ环境下实现奇异值分解最小二乘法并对数据进行分析。结 果该方法既可以获得引起红外光谱变化的组分数及其光谱，又能给出各组分数 随时间的变化，与酸碱平衡原理相结合，获得模拟物质的酸碱平衡常数为ｐＫａ＝ ６．１５。结论　奇异值分解最小二乘法是处理平衡态红外光谱的有效工具。 Aim To set up a least square method based on stoichiometry to analyze the data of equilibrium infrared spectra. Methods A two-component acid-base equilibrium system and its spectral data were constructed by numerical simulation method. The least-squares method of singular value decomposition was implemented in MATLAB and the data were analyzed. Results The method can obtain both the number of spectra and the spectrum of the components which caused the change of infrared spectrum and the variation of each component with time. Combined with the principle of acid-base balance, the acid-base equilibrium constant of the simulated substance is pKa = 6. 15. Conclusion Singular value decomposition least square method is an effective tool to deal with equilibrium infrared spectra.