The invention relates to a test 
system for the extension of a multi-axis and salt-spray 
corrosion fatigue crack. The test 
system comprises a fatigue tester for providing I-type, II-type, III-type and compound fatigue loads required by a test for a 
test sample through a pull-
cut-twist multi-axis loading fixture, and further comprises a salt-spray 
corrosion environmental box, wherein the salt-spray 
corrosion environmental box comprises a salt-spray corrosion box body and a salt-spray pre-occurrence box body which are mutually communicated through a pipeline; the salt-spray pre-occurrence box body conveys air and 
salt water required by salt-
spray forming to the salt-spray corrosion box body; the salt-spray corrosion box body provides a required salt-spray corrosion environment for the fatigue crack extension test; both the pull-
cut-twist multi-axis loading fixture and the fatigue crack extension 
test sample are positioned in the salt-spray corrosion box body. Through the adoption of the test 
system, the fatigue crack extension rate and other 
fracture mechanics parameters under the combined action of multi-axis loads and the salt-spray corrosion environment can be measured relatively well, and thus the 
material selection design and the service 
life evaluation for 
marine engineering equipment serving in the salt-spray corrosion environment and under a complex stress state can be supported.