To implement high-resolution and low-light sensitive three-dimensional (3D) imaging for long-range applications while simplifying data collection and reducing collection time, a polarization-modulated 3D imaging structure, using a large-aperture electro-optic modulator (EOM) and electron-multiplying CCD (EMCCD), is proposed in this paper. As the EMCCD camera itself has no ability of time resolution and high-speed gating due to the time integration mechanism, large-aperture EOMs are used to provide time resolution and high-speed shutter simultaneously for the EMCCD cameras to obtain the polarization-modulated images from which a 3D image can be reconstructed. A narrow field of view was designed to match the divergence of laser beam for long-range imaging, and therefore through the receiver, the incident angle on the EOM would still be limited to within a small angle, which would not degrade the modulation performance significantly during electro-optic modulation. Ultimately, we found that the polarization-modulated 3D imaging lidar showed very promising performance on time-resolved imaging in a field of view of 0.9 mrad.