In this letter, a new single three-dimensional (3D) laser projector is proposed. As liquid crystal (LC) can produce two image patterns with orthogonal polarization states at 120 Hz, only one projector is required in this approach for reconstruction of a 3D object. The light source is made up of RGB (red, green, and blue) lasers because laser has lots of advantages such as longer life, higher brightness, and larger color gamut. A novel diffusive media with good polarization-maintaining quality is used as rear projection screen for its high transmission efficiency (～90%) and low reflection efficiency. When laser incidents into the diffusive media, which contains lots of spherical particles with sizes between 2 and 15 \mu m, laser is scattered randomly and the laser speckle is reduced. A spatial phase mask is also inserted into the optical path to reduce speckle. With these techniques, the speckle contrast is reduced to 0.1 and the quality of image patterns has been greatly improved.