Using the real space self-consistent field theory, the transitions between the body-centered-cubic phases and the cylindrical phases were studied for the diblock copolymers in the external electrostatic fields along three different orientations [001], [110], and [111]. The different orientations of the external fields resulted in the cylinder structures with various symmetries through the intermediate ellipsoid structures, where the cylinder-to-cylinder transition was also observed in the electric field along the orientation [110]. Furthermore, the size of ellipsoid was investigated by varying the strength of electric field, and the factors that affect the critical values of electric field strengths were also considered for the sphere cylinder transitions in the electric fields with orientation [001]. Our findings are compared with the available experimental and theoretical works, which is in a general agreement. (C) 2013 Elsevier Ltd. All rights reserved.