Abstract: Laser Schlieren device was established to observe Rayleigh-Bénard-Marangoni effect produced in thick liquid depth by the diffusion of binary liquid mixtures.A recorder and a camera separately recorded dynamic and static convective flow patterns during experiment.According to different signs of Ma number and Ra number,different binary liquid mixtures were selected to investigate the RBM effect induced by different driven mechanism including density gradient or surface tension gradient or combination of both.Qualitative analysis to experiment results was presented.