【Objective】 To compare the perioperative blood loss between interlaminar and transforaminal approaches by percutaneous endoscopic discectomy in order to provide more reference for guiding the proper choice of surgical methods clinically. 【Methods】 We retrospectively analyzed the clinical data of 160 patients who underwent percutaneous endoscopic lumbar discectomy from June 2019 to November 2020， with 80 patients in interlaminar approach group and 80 in transforaminal approach group. The blood loss was calculated according to Gross formula. 【Results】 The perioperative total blood loss （mL）， hidden blood loss （mL） and hemoglobin loss （g/L） were significantly lower in interlaminar approach group than in transforaminal approach group （119.73±179.26 vs. 158.6±190.65， 109.73±179.53 vs. 148.78±190.19， 3.76±8.12 vs. 4.31±7.62） （P<0.05）. However， there was no significant difference in visible blood loss between the two groups. 【Conclusion】 The perioperative hidden blood loss accounts for a large proportion in percutaneous endoscopic lumbar discectomy. In addition， the interlaminar approach causes less blood loss than the transforaminal approach.