2205 duplex stainless steel is often welded on the surface contact of the corrosive media in projects to prevent stress corrosion in petrochemical facilities. To explore the application scope and feasibility of the solution ,two welding processes (automatic welding and manual welding), three kinds of the common corrosion environment (saturated hydrogen sulfide, magnesium chloride, calcium chloride) are studied by constant load tensile and micro-fracture analysis methods. its stress corrosion is evaluated comprehensively and the mathematical model of stress–life is established based on the experimental results. The results indicate that constant tensile load threshold sth automatic welding is the 0.45RP0.2, manual welding is the 0.4RP0.2 in saturated H2S environment, and the difference is 17%; all the samples remain intact after 96 hours in 0.9RP0.2 stress test of the calcium chloride environment, which shows excellent resistance to chloride stress corrosion. But the material doesn’t work well in the environment of boiling magnesium chloride solution.