Testing sour gas wells safely is still a difficult problem in the world, and testing offshore gas wells with sulfureted hydrogen (H(2)S) presence requires an even higher safety level. But offshore researches published are limited, and standards, principles, regulations and manuals are scattered. Distinctive structures of well bore, well head and surface, and peculiar emergency response plan, are all need deep research. Based on the long term study on high pressure high temperature well development both on land and offshore, a brief introduction about hazards of H(2)S during well testing, and the difference between on land and offshore well testing is given firstly. Then, according to monitoring, alarming and precaution measures to H(2)S effusion in the field, typical potential engineering accidents and treating methods when testing offshore sour wells are studied. The results are helpful to establishing regulations on testing offshore sour wells.