Soil mercury vapour survey is being increasingly carried out in China, and hundreds of atomic absorption mercury vapourmeters have so far been used for this purpose. The high price of gold-filament mercury-catching tube has hin dered seriously the substantial application of this method in production. This paper proposes to use a mercury-catching tube based on physical adsorption by active carbon instead of on routine chemical adsorption by amalgam. It has remarkably higher capacity for adsorption and deadsorption of mercury and can be used repeatedly so as to cut down the cost drastically. This enables any unit equipped with single wavelength atomic adsorption mercury vapourmeter to obtain enough mercury-catching tubes to perform soil mercury vapour sur vey on a large scale.The present paper deals with the optimum operating condition and work ing method for adsorption and deadsorption of mercury by mercury-catching tube, as well as the cause and measures for elimination of interference. In add ition, discussion is given concerning the theoretical existence of interfering gases in soil gas components.Two sorts of mercury-catching tubes recommended in this paper were tested and compared in several deposits, and their experimental application was un dertaken in a gold prospect in Zhejiang. The results show that the active car bon mercury-catching tube and the gold filament mercury-catching tube yield the same geological effect.