In computer aided geometric design, B-spline is an important method for curve and surface modeling, and it is widely used in many applications. For B-spline modeling, we usually need to deal with its elevation in order to keep the same degree between B-spline curves or surfaces with different degrees. Many papers have paid more attention on this problem, and some important results were obtained. But, it is not completely solved by now. In this paper, we present a new approach to elevate cubic B-spline curve, which is based on the relationship matrix between cubic B-spline bases and quartic B-spline bases on each knot segment within the domain of B-spline curve. For this approach, the new control points can be obtained directly for each knot segment. Actually, this method has lower computation, and easily implements.