Spherical, octahedral, and cubic shaped PbSe quantum dots were successfully synthesized by virtue of a green chemical route, using environmentally friendly N,N-dimethyl-oleoyl amide as the solvent of Se. The process eliminates trioctylphoshine from the synthesis, using oleic acid as capping ligand in the noncoordinating solvent. Transmission electron microscopy (TEM), X-ray diffraction (XRD), and energy dispersive X-ray spectroscopic (EDS), were used to characterized the samples. The crystalline size can be tuned in a range from 8 nm to 16 nm by varing the reaction time or growth temperature. Based on the evidence of TEM images, the mechanism of PbSe quantum dots evolution from spherical to cubic structure has also been discussed. We found that the growth temperature played an important role in the morphology of PbSe quantum dots. This finding will enhance our understanding for the formation mechanism of nanomaterials with special shapes.