Simulation of solidification process and the thermodynamic relation between temperature and equilibrium precipitated phases in H13 steel with Nb and high Mo contents have been investigated based on the Scheil module and Ploy-3 module in the Thermo-calc thermodynamic software.Meanwhile

the segregation behavior of alloying elements in the steel tested was also discussed.The result of element segregation was presented and equilibrium partition coefficient of alloy element was obtained by linear regressions depending on the Scheil-Gulliver equation and the Origin8.0 soft.The results show that the mass fractions of C

Nb and V is decreased sharply when solid fraction reaches 90% as a result of MC carbide precipitation.The equilibrium partition coefficients K0 of C

Si

Mn

Cr

Mo

V and Nb are less than 1

which is consistent with literature data.The high temperature homogenizing treatment process atn（1 250

1

270） ℃×（4

6

） hours and multi-passes forging has been suggested

which reduces segregation and improves the comprehensive properties of the steel tested.