Fourier infrared spectrometer and thermal imager can be used to measure infrared spectra and image of conventional liquid rocket plume flow field. The infrared spectral of plume flow field was detected, the main products of combustion H2O, CO2, and traces of combustion products NO and N2O were measured. The plume flow field structure was captured by infrared image, the relationship between the image characteristics and combustion state was set up. The results show that the infrared spectrometer and infrared thermal imager can accurately measure characteristics of plume flow field combustion products, the flow field structure and the application of infrared technology for the engine work condition monitoring provides a new analysis method.