Abstract: The effects of microstructure on the stress relaxation behavior of alloy BT14 were studied at 200,400 and 600 ℃.The results show that Widmanstaten microstructure has relatively high stress relaxation resistance at 400 and 600 ℃,while the equiaxed microstructure is more relaxation-resisitant at 200 ℃.The relationship between plastic strain rate and stress during stress relaxation is obtained by stress relaxation method,and rate stress index and deformation active energy are calculated.