Background:At present, there are two techniques which are widely applied clinically, including midline technique and paramedian technique,both of them are difficultfor residents when faced with elderly.We aim to explore the feasibility of ultrasound-assisted modified paramedian technique for spinal anesthesia in elderly,in order to provide clinicians with a new and easy-to-operate technique.Methods:A total of 150 elderly patients who were scheduled for urology surgery under spinal anesthesia in our hospital were randomly divided into three groups (n=50) : midline technique group ( group M), paramedian technique group ( group P) and modified paramedian technique group ( group PM) with 50 patients in each group.All spinal anesthesia were performed by the same second-year resident.Results:Compared with groups M and P , group PM had a significantly higher first-attempt success rate (P<0.05,specially in patients aged 65-74 years)，fewer attempts（P<0.05）and higher patient satisfaction score（P<0.05）. Compared with group M,the time taken to perform spinal anesthesia and the number of needle redirections were significantly reduced in group PM (P<0.05), and there was no statistically significant difference between groups PM and P . There were no statistically significant differences in the cases of inconsistency between ultrasound-assisted and landmark-guided location of intervertebral space, the time taken to ultrasound-assisted location,the onset time to pain block at T10,the incidence of hypotension ,anesthesia effect and the incidence of headache, low back pain, nausea and vomiting within 24 hours after surgery.Conclusions: The modified paramedian technique in spinal anesthesia for elderly patients can significantly improve the first-attempt success rate, reduce the number of attempts and reduce procedure time and the damage to patients’ tissue during operation. Compared with the traditional midline and paramedian techniques, modified paramedian technique achieves complementary advantages of the others,easy to learn,which effectively solves the difficulty of spinal anesthesia during the procedure in elderly patients and provides a new operation path for lumbar puncture.It is worthy of further research and application.Trial registration:Prospectively registered at China Clinical Trial Registry, registration number ChiCTR2100047635, date of registration: 21/06/2021.