Simulated calculation and analysis on equilibrium precipitated phases MBC6 and ferrite as well as non-equilibrium solidification of martensitic stainless steel 9Cr18Mo ( % ： 0. 95 〜1. 10C

16. 6 ~ 18. 0Cr

0. 4 - 0. 7Mo) have been carried out by using Thermo-Calc thermodynamic calculation software. Results show that during solidification the segregation of C

Cr

Mo and Fe in steel 9Cr18Mo is rather serious

the C and Cr content in steel have definite effect on the precipitated amount of M

23

C

6

and the elements such as Cr and Fe content in M

23

C

6

and in matrix

while the change of Mo content in steel only effects on the precipitated amount of M

23

C

6

and the Cr and Mo content in M

23

C

6

.