Abstract: When carbon fiber reinforced polymer ( CFRP) was used in the actual steel structure reinforcement projects，structural failure often occurs due to the cyclic temperature and humid environment． This paper presented an experimental study on the tension capacity of 8 steel-CFRP strap joints including 2 specimens after 90 wet-dry cycles and 2 specimens after 180 wet-dry cycles． The ultimate bearing capacity，the failure characteristics of the steel and CFRP interface were studied after dry-wet cycles． The test results showed that steel-CFRP strap joints tensile bearing capacity decreased significantly under the influence of wet and dry cycles． Bearing capacity of the specimens stabilized after 90 times of wet-dry cycles． And through theoretical formula it was deduced results of maximum principal interface stress，which were compared with the test results and a deviation between the two was within 15%． Which verified the accuracy of theoretical formula．