Objective To observe the changes in intradiscal internal internal pressure before and after percutaneous nucleoplasty (PN) in the patients with discogenic low back pain (DLBP),and to explore the mechanism of PN for alleviating DLBP.Methods Thirty patients definitely diagnosed as DLBP undergoing PN in the orthopedic department of this hospital from June 2023 to October 2023 were selected.The internal pressure of the lumbar disc was measured before and after the surgery.The visual analog scale (VAS),Japa-nese orthopedic association score (JOA) and Oswestry disability index (ODI) were used to assess the pain level of the patients before operation and at postoperative 1 d,1 month,3 months.The surgical efficacy was e-valuated by using the modified MacNab criteria.The linear correlation analysis was used to observe the relation-ship between the internal pressure of lumbar disc and changes in each pain score,and the factors possibly affecting postoperative effect was analyzed by using the multivariate logistic regression analysis.Results Compared with be-fore the surgery,the immediate postoperative internal pressure of lumbar disc in the patients was significantly decreased.The JOA scores at postoperative 1 d,1 month and 3 months were significantly increased,while the VAS and ODI scores were significantly decreased,and the differences were statistically significant (P<0.05). The excellent rates of surgical efficacy at postoperative 1 d,1 month and 3 months were 66.7％,73.3％ and 63.3％,respectively.The internal pressure of lumbar disc difference value between before operation and on postoperative 1 d and internal pressure of lumbar disc decrease rate had no significant correlation with the change value of each pain score (P>0.05).The multivariate logistic regression analysis showed that the dis-ease duration and the decrease rate of internal pressure of lumbar disc were the influencing factors of clinical efficacy in PN (P<0.05).Conclusion The occurrence of DLBP may be related with the increase of internal pressure of lumbar disc.PN could effectively reduce internal pressure of lumbar disc and achieve the goal of pain relief.