Abstract: The development of single photon emission computed tomography imaging has stepped into a molecular level since the last century. Receptor imaging has been one of hotspots in the current nuclear medicine imaging research, especially the somatostatin receptor scintigraphy. Octreotide, a frequently used somatostatin receptor in the clinic, has been labeled with lots of radioisotopes such as ¹¹¹In, ¹²³I, ⁹⁹Tc^m, ⁹⁰Y. Earlier studies have demonstrated that the direct and indirect labelling methods of ⁹⁹Tc^m-octreotide have been relatively mature and have a high labeling efficiency. And SPECT imaging with ⁹⁹Tc^m-octreotide has a high accuracy in finding somatostatin receptor-positive lesions especially gastrointestinal neuroendocrine tumors. ⁹⁹Tc^m-octreotide, a promising somatostatin receptor imaging agent, will be widely used for clinical imaging.