We prove local well-posedness for the Cauchy problem associated to Kortewegde Vries equation on a metric star graph with three semi-infinite edges given by one negative half-line and two positives half-lines attached to a common vertex, for two classes of boundary conditions. The results are obtained in the low regularity setting by using the Duhamel Boundary Forcing Operator, in context of half-lines, introduced by Colliander, Kenig (2002), and extended by Holmer (2006) and Cavalcante (2017).