Under the combined action of the laser and arc， the effects of activating fluxes(SiO

2

、 TiO

2

、CaF

2

) on YAG Laser-TIG Arc hybrid welded 1Cr18Ni9Ti stainless steel are studied. The results show that all three activating fluxes can deepen the welding penetration

and SiO2 and TiO2 can remarkably increase penetration. By comparison and analysis of arc shape

peak temperature of temperature testing curve.The arc shrinks are found in relation to using of activating fluxes

meanwhile. Activating flux can also effectively restrain laser plasma. Actually

The two factors increase peak temperature of temperature curves in weld center.And the weld penetration depth and aspect ratio increase at the same time.