In order to simulate the carbon steel corrosion in oil-gas field produced water containing H₂S, a proper artificial water was poured into an autoclave and then into which H₂S gas was introduced respectively in two different ways: directly inducing H₂S from a pressed H₂S gas cylinder and generating H₂S gas in-situ during the corrosion process through chemical reaction of desired reagents pre-set in the water. The corrosion rates of 20# steel were comparatively studied for two different ways of introducing H₂S gas, while the other parameters kept the same, by weight loss technique, electrochemical measurement and scanning electron microscopy with energy dispersive spectrometer. It has been found that the 20# steel in the water with in-situ generating H₂S exhibits a corrosion rate 0.1077 mm/a and a coarse and porous corrosion product film. Whereas, those by inducing H₂S from gas cylinder are a corrosion rate 0.0518 mm/a and a uniform and compact corrosion product film respectively. It is also noted that the results of the former one are better accorded with those observed in oil/gas fields practice. Therefore, the way of directly inducing H₂S from gas cylinder into the waters should be suitable to simulate the relevant corrosion performance of metallic materials in oil-gas field produced waters.