In a platetype bioreactor for biofilm development, the experiments for the growth characteristic of highefficiency hydrogenproduction photosynthetic bacterial biofilm was undertaken under three different monochromatic light source with light wavelengths varied from 420 nm to 590 nm. The effect of light wavelength on the parameters of Rhodoseudomonas palustris biofilm is discussed, such as the surface coverage rate, thickness, dry weight, and density. The light wavelength has significant influences on the growth rate and structure of biofilm. Increased wavelength results in a higher surface coverage rate. While the dry weight of biofilm keeps almost constant at the same period. After 4 days, the thickness of biofilm decreases with the increase in light wavelength while longer light wavelength leads to higher density of biofilm, which results from the cell division and production of EPS by short light wave.