Abstract: A simulation method is presented for heat convection in 3D complex geometries.For a non-orthogonal coordinate formulation of the governing equations with cartesian velocity components,pressure and temperature,a finite volume method is utilized for discretization,SIMPLER algorithm is applied to pressure-velocity coupling,and the cell-face velocity interpolation method is employed for overcoming the pressure oscillations associated with the nonstaggered grid system.A visualization computing software is deve loped and applied to prediction of the heat convection in the cooling passage of low heat rejection engine.