In this paper, the purpose is to study the biological effects of platymonas subcordiformis irradiated by polarization and non-polarized laser, such as promoting, pigment chlorophyll content and absorption spectra of pigment extracts. The platymonas subcordiformis were irradiated by the argon laser at 488 nm, 70 mW output power. The number of algae cells were counted by sampling in two days interval, and after culturing six days, the chlorophyll was extracted and its content to be detected and the absorption spectrum of chlorophyll to be scanning. The result showed that, for the platymonas subcordiformis irradiated by polarization and non-polarized laser, the effect of growth promoting was not clear distinction, the cumulative of chlorophyll content was not different, and the absorption spectrum of pigment extracts did not vary also. On our reseach conditions, whether the laser on polarization or not are all the effective role of biological effects of platymonas subcordiformis. The relation of laser polarization and laser biological effects is to be further studied.