The flame spectrum detection technology applied to the effective monitoring of gasifier can reflect the working condition of gasifier in real time and guarantee the stable operation of gasifier. Based on the bench-scale entrained flow gasifier, the different chemiluminescence characteristics at different axial positions of the impinging plane (L) of coal-water slurry (CWS) flame are studied by the spectrometer, and the reaction zones in gasifier are characterized by different radical intensity and distributions. The results show that: OH*(306.7 nm, 309.8 nm), H*2 (382 nm), CH*(314.5 nm, 387 nm), Na*(589 nm), Ar(671 nm)and K*(404 nm, 768 nm, 770 nm) characteristic peaks can be detected in the range of 300～800 nm. Different particle distributions can be used to characterize the macroscopic characteristics of flame. There is also a strong background radiation in CWS gasification flame. The background radiation mainly comes from the blackbody radiation generated by coal particles at high temperature and continuous rotational radiation of 350～600 nm generated by CO*2. The strong background radiation will interfere with the determination of free radical intensity radiation, which will be deducted by the calculation. The distribution of OH* can be used to characterize the flame reaction region, while CH* only exists in a relatively narrow reaction region of -10 cm