介绍了基于开放光路傅里叶变换红外光谱学(OP-FTIR)技术监测偏二甲肼的方法。该方法具有响应速度快，非接触测量，能实时在线监测，测量系统稳定可靠等特点，较其它的方法有很大的优势。利用该测量系统对环境中的偏二甲肼进行测量，得到吸收光谱，再使用 Marquardt非线性最小二乘法进行浓度反演。测量结果表明，系统能正确地测量偏二甲肼的浓度变化信息。光谱分辨率为 1 cm－1，时间分辨率可达 4s，并具有很高的信噪比。浓度在 1 ppm以下， UDMH测量误差为 10%左右，能够很好地满足实际应用。通过比对实验，进一步验证了测量原理及测量方法的正确性。

This article introduces a method of monitoring Unsymmetric Dimethyl Hydrazine(UDMH) based on Open Path Fourier Transform Infrared (OP-FTIR )Spectrometry technology. There are many advantages about this technology in monitoring gases, such as quickly response, non-touch, monitoring gases on-line real-time ,stable measuring system and so on. We made use of the measuring system to monitor the UDMH gas and got its absorption spectra. Quantitative analysis was performed by means of the Marquardt nonlinear least square method. After that, we could know measuring system could correctly get concentrations information. Spectra resolution was 1cm-1. Time resolution could reach 4s and it had a high Signal-to-Noise. The measuring errors could be held at ten percent around when concentrations was below 1ppm. Naturely, those advantages could meet the practical application. After the contrast experiment, we knew that our measuring principle and method were right in monitoring UDMH gas concentrations.