Safety assessment is a very important means to ensure safety production. It needs considering a lot of factors and has high degree of fuzziness. In this paper, a new safety assessment method-the fuzzy comprehensive safety assessment method is introduced first. Then, it is applied to the safety assessment of three hazardous gas tanks. They include one-hydrogen gas tank with 600 m(3) in volume and 55kPa in pressure, one coal gas tank with 10 000 m(3) in volume and 40 kPa in pressure, and one oxygen gas tank with 60 m(3) in volume and 1000 kPa in pressure. The assessment results show that although they are all hazardous, the coal gas tank is the most hazardous one, the oxygen gas tank is the least hazardous one among them. Finally, four safety measures are suggested: (1) The safety interlock equipment should be added for the 10 000 m(3) coal gas tank and the 600 m(3) hydrogen tank to increase their intrinsic safety degree. (2) The number of the gas detection equipment should be increased and the time intervals of the detection should be shortened so that the potential spillage of coal gas or hydrogen can be detected and effectively treated as soon as possible. (3) The safety regulations and systems should be further built and improved, including the accident emergency rescuing and aiding system, the safety production responsibility system, and the total quality- and-safety management system. (4) More safety education and training should be carried out for the staffs so that their safety consciousness can be strengthened and their safety skills can be raised.