The invention discloses a multi-function extension clamp for a material fatigue test, which is used for clamping metal tubes with equal wall thickness and solid smooth clamping rods in fatigue tests at a normal temperature and a high temperature. A main shaft is provided with a mandril (12), a limit lug boss (11), a middle threaded section (8) and a clamping section (13); the main shaft is connected with a sleeve (3) through a cage nut (2), and the cage nut is screwed on the middle threaded section (8) of the main shaft; and a transition mandril (5), a clamping cushion sleeve (4) and the mandril (12) on the main shaft are arranged in the sleeve (3). The multi-function extension clamp can be used for single-shaft, pure-torsion and shaft-torsion compound fatigue tests on the tubes with equal wall thickness and the solid smooth clamping rods in various specifications at the normal temperature and the high temperature. The multi-function extension clamp has the advantages of simple structure, large application range of sample size, good clamping function, and sample material saving.