Color helium bubble flow visualization is a new and unique technique. Flow visualization in the wind tunnel using color helium bubbles has recently been achieved at the Harbin Aerodynamic Research Institute. Rich and varied color paths are obtained. This paper describes a unique principle of light interference for flow visualization with color helium bubbles. The different colors of the helium bubbles depend on the wavelength of light, the refractive index and thickness of the bubble film, and the angle of reflection in the bubble film. Methods for controlling these four parameters are indicated. A formula for the bubble film-thickness calculation is derived. The corresponding relation between the bubble film thickness and other parameters is calculated. Typical flow-visualization photographs are presented. An appraisal of the significance of color helium bubble flow visualization is given.