In this paper, we introduce and study the conformal mean curvature flow of submanifolds of higher codimension in the Euclidean space R n . This kind of flow is a special case of a general modified mean curvature flow which is of various origination. As the main result, we prove a blow-up theorem concluding that, under the conformal mean curvature flow in R n , the maximum of the square norm of the second fundamental form of any compact submanifold tends to infinity in finite time. Furthermore, by using the idea of Andrews and Baker for studying the mean curvature flow of submanifolds in the Euclidean space, we also derive some more evolution formulas and inequalities which we believe to be useful in our further study of conformal mean curvature flow. Presently, these computations together with our main theorem are applied to provide a direct proof of a convergence theorem concluding that the external conformal forced mean curvature flow of a compact submanifold in R n with the same pinched condition as Andrews-Baker's will be convergent to a round point in finite time.2000 Mathematics Subject Classification. Primary 53A30; Secondary 53B25. Key words and phrases. conformal mean curvature flow, conformal external force, blow-up of the curvature, round point.