A novel toroid-structured coated nano particle (T-CNP) antenna with active core (doped with rare earth ion Er3+) is investigated in this paper. It is observed that the active T-CNP can achieve a scattering gain at a frequency near 600THz. The size of the gain is affected greatly by how the T-CNP antenna is illuminated with the incident plane wave. The gain of the T-CNP antenna with its axis along the direction of the incident E-field is 27.5dB, while it is only 1.0 dB when the axis of the T-CNP antenna is parallel to the incident wave vector. With the T-CNP antenna's axis parallel to the incident E-field, the antenna responds in a resonant dipole mode.