Abstract. An interaction equation of the capillary-gravity wave is considered. We show that the Cauchy problem of the coupled Schrödinger-KdV equation,is locally well-posed for weak initial data u 0 × v 0 ∈ L 2 (R) × H −1/2 (R). We apply the analogous method for estimating the nonlinear coupling terms developed by Bourgain and refined by Kenig, Ponce, and Vega.