Background and Objective: Hypocalcemia after thyroidectomy surgery is one of the common and important complications that can lead to serious clinical complications. In this study, factors related to the occurrence of hypocalcemia after thyroidectomy are investigated. Materials & Methods: The present study was an analytical cross-sectional study that was conducted with the aim of determining the factors related to the occurrence of hypocalcemia after thyroidectomy in Shahid Beheshti Hospital, Qom during 2012-2019. Factors related to hypocalcemia were measured in these patients. Finally, all information was entered into SPSS version 22 software and analyzed with t-test and chi-square statistical tests. Results: The average age of patients participating in this study was 42.16 ± 11.97 years. 47 patients were male (12.7%) and 322 were female (87.3%). 70 patients (19%) had thyroid malignancy, 28 patients (7.6%) had Hashimoto's disease, 68 patients (18.4%) had Graves' disease, and finally 183 patients (49.6%) had multinodular goiter. The level of Ca after surgery in three stages (Immediately, one and six months after surgery) did not have a statistically significant difference based on the type of thyroidectomy surgery, thyroid cancer, Hashimoto's disease and multinodular goiter, the duration of surgery, hematoma (P > 0.05), but calcium one month after surgery in Graves and Voxani patients who had recurrent nerve damage had a statistically significant relationship (P < 0.05). Conclusion: Identifying and accurately understanding the factors related to the occurrence of hypocalcemia after thyroidectomy is very important in improving surgical results and reducing side effects. It is recommended that physicians carefully identify risk factors and employ appropriate preventive strategies, including monitoring calcium levels and prescribing necessary supplements.