Based on spherical cap-shaped nucleation process at heterogeneous particles surface, a numerical model of heterogeneous condensation flow was established. The condensing flow with heterogeneous condensation in a nozzle and a turbine cascade was numerically studied. Results shows in heterogeneous condensation, if there are enough heterogeneous particles, the steam can focus on the nuclear and begin to condense immediately after the state path crosses the vapor-saturation line. Nucleation process which takes place at heterogeneous particles surface could depress the spontaneous condensation, and the inhibited degree is determined by the concentration of heterogeneous particles. The heterogeneous condensation can affect the flow pattern, reduce the strength of condensation shock in nozzle, and optimize pressure distribution, weaken the boundary layer separation, and reduce the thermodynamic losses of non-equilibrium condensation in turbine cascade.