2,4,6-trimethylbenzoyl-diphenyl phosphine oxide(TPO) is a widely used photoinitiator in UV-LED photocuring formulations.Due to reproductive toxicity,the search for its replacement has received a lot of attention in recent years.The eco-friendly 2,4,6-trimethylbenzoyl-dimethylphenyl phosphine oxide(TMO) was evaluated.The photophysical,photochemical properties and application of TMO in waterborne UV varnish were studied and compared with that of TPO.The results showed that the photo absorption,photobleaching and thermal stability of TMO were better than those of TPO,and the solubility of TMO was the same as that of TPO.The properties of TMO and TPO were the same in color difference and glossiness,while the mobility of TMO in various solvents was much lower than that of TPO,which had good environmental security.