Abstract: The susceptibility to stress corrosion cracking (SCC) of nickel based alloy 825 was studied in supercritical water (SCW) at 550 ℃/25 MPa, 600 ℃/25 MPa and 650 ℃/25 MPa respectively, and their general corrosion behavior was researched in supercritical water at 650 ℃/25 MPa and in subcritical water at 290 ℃/15.2 MPa respectively. The strain-stress curve obtained from slow strain rate tensile tests (SSRT) shows that the strength and elongation of alloy 825 decrease with the increase of temperature. The ex-situ scanning electron microscopy shows that the SCC susceptibility of alloy 825 is 600 ℃＞550 ℃＞650 ℃. The general corrosion experiment in SCW shows that the weight gain is subject to power function growth rule, while the one in subcritical water indicates the weight loss and then weight gain.