Abstract: Objective To evaluate the efficacy of formaldehyde fumigation destroying HBV taking HBsAg as index.Methods Three kinds of carriers (stainless steel,emulsion round plates with diameter of 1.0cm,and cloth square plates with 1.5×1.5cm²) were prepared.20 μl of HBsAg suspension (100μg/ml) containing 1% calf serum with phosphate buffer was droped on each carrier.The carriers were dried in an incubalor (37℃) for 2 hours,then kept in refrigerator (4℃) before used.Formaldehyde fumigation was conducted in the fumigator HBsAg was tested by SPRIA.Results The efficacy of fomlalde-hyde fumigation destroying HBsAg was directly proportional to the paraformaldehyde dose under the conditions of sterilizing 2 hours,temperature 25℃,relative humidity 75%.While paraformaldehyde dose reached 20g/m³,the HBsAg on all 3 kinds of carriers was destroyed.The efficacy of formaldehyde fumigation destroying HBsAg was directly proportional to the sterilizing hours(under the conditions of paraformaldehyde dose 10g/m³,temperature 25℃,relative humidity 75% ).While formaldehyde fumigation hours reached 5 hours,the HBsAg on the emulsion and cloth plates was destroyed,but on stainless steel plates was not.Conclusion It was suggested that the rough surface of material retain more fomlaldehyde gas and the HBsAg on it was destroyed easily,the smooth surface of material retain less formaldehyde gas and the HBsAg on it was destroyed difficultly.