The powers of back-scattering light from bubbles at various distances and with various densities were calculated by the Lambert-Beer law and were measured by the laser power meter. The results from data indicated that the power of back-scattering light was enhanced due to bubbles,but it is still very feeble.The power related to the distance between the detector and the bubble film can be calculated by the Lambert-Beer law.The power is related to the density of bubbles.