The mutual control of magnetism and ferroelectricity is a longstanding goal of the investigation on multiferroicity, which offers the potential applications in multifunctional magnetoelectric devices. It has been observed in a variety of materials that the ferroelectric behavior can be controlled by magnetic field effectively, but the magnetic behavior is hard to be tuned by electric field ( E ) in most cases. The present work predicts that the magnetization ( M ) can be well controlled by E in conical spin structure. When E rotates in the plane normal to the magnetic modulation vector, M is driven by E to rotate continuously without any noticeable decay. This magnetoelectric tunability is attributed to the flexible rotation of conical spin structure.