Use of aluminium materials has increased in the vehicle industry in the last years due to their low weight. Machining of aluminium by industrial lasers is a more complex task than that of steel because of the lower absorption, higher heat conduction, higher heat capacity and oxide layer on the surface. The low absorption ability of the Al surface can be significantly improved by using appropriate brazing flux suspension on the wavelength of CO2 lasers. In this paper the role of brazing flux components and their influence are investigated in the heating efficiency in case of Nd:YAG lasers, which are widely used in the laser joining technology. This research work presents the differences between the effects of the brazing flux in case of CO2 and Nd:YAG lasers.