In order to investigate the influence of low level laser irradiation on the process of blood oxygenation,He Ne laser is used as the source of radiation.The blood is taken from the vein of a healthy man.Samples of the blood are divided into laser groups and control groups.Each sample contains 3 ml blood.The power of laser is 2 mW,and the time of irradiation 2 min.Oxygen is injected into each sample respectively step by step.Each step of oxygen injection lasts 10 secs.Six steps of oxygen injection are arranged for each sample.Oxygen saturation is tested immediately after each step.The result indicates that the laser irradiation can increase obviously the oxygenation rate of the blood if the oxygen injection is operated about 20 min after the laser irradiation.This result implies that the laser irradiation can influence the process of blood oxygenation.