Objective To observe and evaluate the clinical effect of the new fenestration rammer in the treatment of thoracolumbar burst fracture by posterior internal fixation and reduction of lamina with finite fenestration decompression. Methods Patients with thoracolumbar burst fractures admitted to Zigong Fourth People’s Hospital between September 2017 and January 2020 were retrospectively selected. The patients were divided into observation group and control group according to different surgical methods. The observation group used a new tamping device with finite fenestration rammer of unilateral lamina to reduce the spinal occupying bone mass, and the control group used conventional instruments for reduction of intraspinal fracture masses. The operation time, intraoperative blood loss, CT measurement of sagittal diameter ratio of spinal canal and the number of cases of postoperative vertebral empty shell phenomenon were recorded in the two groups, and Frankel grading evaluation of spinal nerve function was conducted. Results A total of 67 patients were included. There were 33 cases in the observation group and 34 cases in the control group. The patients in both groups were followed up for 12 to 16 months, with an average of (14.45±2.25) months. The improvement rate of Frankel rating in each group was 100%. In the control group and the observation group, except for the sagittal diameter ratio of spinal canal before operation (P=0.616), the operation time [(150.44±26.47) vs. (120.91±20.86) min], the intraoperative blood loss [(244.41±42.97) vs. (183.33±34.56) mL], the sagittal diameter ratio of spinal canal one week after operation [(92.50±2.32)% vs. (93.72±2.40)%], the sagittal diameter ratio of spinal canal at the last follow-up [(91.50±2.96)% vs. (93.17±3.27)%] and the occurrence of empty shell phenomenon (13 vs. 5 cases) were statistically significant (P<0.05). The intragroup comparison showed that the sagittal diameter ratio of spinal canal was improved one week after operation and at the last follow-up compared with that before operation (P<0.05), there was no significant difference in the sagittal diameter ratio of spinal canal between one week after operation and the last follow-up (P>0.05). Conclusions The new fenestration rammer can effectively reduce the spinal occupying bone mass in thoracolumbar burst fracture, effectively restore the volume of the spinal canal, achieve the purpose of decompression, effectively prevent the formation of vertebral shell, maximize the retention of the stable structure of the posterior column, and avoid iatrogenic nerve injury. It is safe and effective.