Abstract: Hemp powder was treated by separate technological operations,such as ball mill grinding,acid treatment and alkali treatment.Then the structure,apparent morphology and sun-screening performance of the treated samples were characterized by infrared spectroscopy,scanning electron microscope,UV-vis spectrophotometer and sun protection factor (SPF) measurement.Experimental results showed that,the upgrading effect for UV absorbance within whole wavelength range by simple increase of hemp powder mass fraction is very limited.Effect of increase of treating time of ball mill grinding for improving light absorbance is not obvious.Comparing the samples that treated by separate kinds of acid and the sample without any treatment,results showed that the sample treated by acetic acid displays the highest light absorbance.Comparing the samples that treated by separate kinds of alkali and the sample without any treatment,results showed that the sample treated by triethanolamine displays the highest light absorbance,even higher than that treated by acetic acid.After the treatment of acid or alkali,the peak intensity of infrared absorption of the hemp powder decreases,but its irregular chip structure remains unchanged.Comparing the SPF of samples that treated by separate methods,results showed that the sample treated by alkali displays the highest SPF value.

Key words: additive of sun-screening cosmetics, hemp powder, sun-screening performance