This paper considers the problem of designing optimal vector smoothing spline curves with equality and/or inequality constraints. The constraints are assumed to be cross-coupled among the element curves imposed at some time instant as well as over some time interval. The vector splines are constituted employing normalized uniform B-splines as the basis functions. Then various types of constraints are formulated as linear function of the so-called control points, and the problem is reduced to convex quadratic programming problem. The performance is examined by some numerical examples.