Based on international experience，the rural labor transfer of China still has big space，however，the “labor shortage” phenomenon differently appears in the different regions of China，it seems that “Lewis turning point emerges” and that rural potential labor transfer is exhausted. Currently the information asymmetry of China’s labor market is a main reason for the above phenomenon. By introducing brand signal into the theoretical model of labor market，the analysis shows that it is feasible and necessary to use brand signal to identify the labor quality in labor market and that the sufficient and necessary condition for bringing labor brand signal identification mechanism into play is that the utility gap harvested from high quality labor and low quality labor stays at the costs from the transfer as a brand form between high quality labor and low quality labor. Thus，both increasing the transfer cost of low quality labor as a brand form and decreasing the transfer cost of high quality labor as a brand form are more conducive to bringing the function of the brand signal to identify labor quality into full play，are more effective to solve information asymmetry problem in labor market and are further helpful to realize the stable and long-term role in rural labor transfer. China should actively support labor brand construction，attach the importance to the standardization and formalization of labor brand，establish industrial associations and output sites of labor brand，enhance the punishment and investigation on fraud labor brand，and accelerate the citizenization process of brand labor.