Objective To investigate the number and location of parathyroid glands in relation to thyroid gland, to increase the knowledge about anatomical variation of parathyroid glands, and to reduce injury of the parathyroid and recurrent laryngeal nerve. Methods A total of 50 cadavers were sectioned. The number and distribution of parathyroid glands and their relations with adjacent structures were observed. Results Mean number of parathyroid glands in one individual was 3.52±0.48, mainly located at the retro-medialis of thyroid, which was called “tri-domain and one area”. Superior parathyroid glands were mainly located in the area of cornu inferior thyroidal cartilage; the inferior parathyroid glands except ectopic parathyroid glands were located in radix nasi of thyroid glands; while the area around inferior thyroid artery contains both the superior and inferior parathyroid glands. These three areas constitute the region of retro-medialis of thyroid that parathyroid glands were inclined to get injured. Most superior parathyroid glands were located beside the lateral of recurrent laryngeal nerve （67.8%） and the inferior parathyroid gland mainly located next to recurrent laryngeal nerve （71.9%）, both showed statistical significance (P＜0.005). About 85.0% of superior parathyroid located in the area around posterior suspensory ligament of thyroid, and most common place for ectopic parathyroid gland was around lingual lobe of thymus (28.6%). Conclusion With extreme caution, familiarity with anatomy and skillful technique, the injury to parathyroid glands and recurrent laryngeal nerve can be prevented, which may not be a restrain of putting standard thyroid operation into practice.