Abstract: The viewpoint in reference that nonzero divergence of electric field E = ±v ×B has nothing to do with electric charge density is challenged. It violates the covariance of Maxwell equation, and the true situation is that the divergence equals still to zero. Taking uniform magnetic field as an example, calculations in uniformly rotational reference system by curvilinear coordinates and Cartan comoving tetrad are performed. It is shown that the covariance of Maxwell equations is retained.

Key words: eovanance, curvilinear coordinates, Cartan comovmg tetrad, covarmnt Oenvative