Hydrogen energy has quietly become the key to dealing with various environmental problems and energy transformation. With the development of the hydrogen energy industry, safety problems caused by hydrogen leakage also occur continuously. It is particularly important to find a safe and reliable visualization technology to detect hydrogen leakage. Some issues about background oriented schlieren and laser beam profile deformation in visualizing and diagnosing flow fields are summed up and studied both theoretically and experimentally. The two optical methods are compared from two aspects of flow field structure visualization and parameter diagnosis. On this basis, the feasibility of combining the background oriented schlieren with the laser beam profile deformation method to visualize and diagnose the flow field is proposed, and an experimental device is established. In addition, the hydrogen flow field is selected as an empirical example. The experimental results show that the combination of background oriented schlieren and the laser beam profile deformation method may be a reasonable and feasible means for complex flow field structure visualization and parameter diagnosis.