A vector expression of the dilatotion field of a segment of dislocation line was obtained with isotropic elasticity. The interaction potential field between a geometric kink, made of straight segments or a smooth curve of dislocation, and a point defect was thus obtained. The distribution of the potential along the dislocation tube for different types and widths of kink was calculated numerically.The possibility of the dislocation relaxation associated with the interaction between a mobile vacancy and the geometric kink on screw and mixed dislocations was analysed.