Abstract: Double diffusive convection during static crystallization was studied. A Laser Swept Velocimetry (LSV) was used to measure the thermo - solutal convection velocity vector field. A mathematical model for static crystallization based on the reassessment of Bennon and Incropera model was derived, and the continuum conservation equations were solved with SIMPLER algorithm. The comparison of simulated and experimental results was examined as discussed. Although the experimental temperature, concentration and velocity profiles were in good correspondence with the calculations, the experimental fluid flow field was likely to be more complex than the somewhat idealized system simulated in this work. It was also shown that the low densiy liquid layer with low temperature in the mushy zone would result in the initiation of double - diffusive convection. With the development of such a convection, the flow velocity, temperature and concentration distributions showed salt fingers pattern. Double diffusive convection would also result in the formation of channel flow in the mushy zone.