Two sound field separation techniques based on equivalent source method are proposed:one is based on the double-layer pressure measurements and the other is based on the single-layer pressure-velocity measurements. In this paper, a sound field separation technique based on equivalent source method but using the double-layer velocity measurements is proposed. First, the theoretical description of this technique is given, and then numerical simulations and experiments are conducted to demonstrate the validity of this technique. By comparison with the technique based on double-layer pressure measurements, the superiority of the proposed technique in separating particle velocity field is shown. And also, in the numerical simulations, the influences of the strength of disturbing source and the distance between two measurement planes on separation accuracy are investigated.