The invention discloses Sn-Ti-Ag ternary alloy welding flux for quartz glass sealing. Tin serves as a matrix of the ternary alloy welding flux; according to the weight percents of introduced Ti and Ag, Ti ranges from 0.1% to 1.6%, and Ag ranges from 0.1% to 2.0%; the atomic percent of introduced O ranges from 0.05% to 3.9%; and the mass percent of impurities in the ternary alloy welding flux is smaller than or equal to 0.1%. The welding temperature range of the ternary alloy welding flux ranges from 650 DEG C to 800 DEG C, and the welding vacuum degree is smaller than or equal to 5*10<-3> Pa.In the quartz glass sealing process, the ternary alloy welding flux needs no scaling powder, the quartz glass sealing technology is simplified, and vacuum sealing reliability of the ternary alloy welding flux is improved. The ternary alloy welding flux can be widely applied to quartz glass sealing and can be applied to welding of quartz glass, glass with the softening temperature not lower than 80DEG C and with SiO2 as the main component, a titanium material, oxygen-free copper, metal with titanium plating layers on surfaces and the like, the ternary alloy welding flux is especially suitablefor preparing a pulse xenon lamp, the service life of the pulse xenon lamp can be remarkably prolonged, and the work reliability of the pulse xenon lamp can be remarkably improved.