An experimental scheme was established for noninvasively measuring the characteristics of light propagation along human meridian direction. The diffuse emittance of the arm skin along the pericardium meridian and non-meridian directions for 658 nm light radiation were measured. The influence of the light chopped frequency and the meridian block on the detected signal was investigated. Our study suggest that the light attenuation along both the meridian and non-meridian directions conforms to definite law. There is a high significant difference between the propagations along the meridian direction and non-meridian direction (P<0.01). Furthermore, the chopped frequency and the meridian block can affect the detected signal. The diffuse emittance signal decreases with the chopped frequency’s increment in the range of low frequency(10-370 Hz), and the relative difference of detected signal along meridian and non-meridian directions increases with the block force’s increment. These research results are important and valuable for interpreting the human meridian phenomena and the physical-chemical characteristics of acupuncture point and meridian by biomedical optics.