The aim of the study was to evaluate the clinical effect of the limited area decompression, intervertebral fusion, and pedicle screw fixation for treating degenerative lumbar spinal stenosis (DLSS) with instability. Hemilaminectomy decompression, intervertebral fusion, and pedicle screw fixation for treating DLSS with instability as the control group.Follow-up of 54 patients (26 males and 28 females; average age, 59.74 ± 10.38 years) with DLSS with instability treated by limited area decompression, intervertebral fusion, and pedicle screw fixation (LIFP group), and 52 patients as control group with hemilaminectomy decompression, intervertebral fusion, and pedicle screw fixation (HIFP group). We assessed clinical effect according to the patients’ functional outcome grading (good to excellent, fair, or poor), Oswestry Disability Index (ODI) and visual analogue scale (VAS) for low back pain and lower limb pain, which was administered preoperatively and at 3, 6, and 12 months postoperatively. Fusion status was assessed by radiologists at the last follow-up. Treatment satisfaction was assessed according to the subjective evaluations of the patients.At the 12-month follow-up, 96.2% (52/54) and 90.3% (47/52) of group LIFP and HIFP belonged to good to excellent outcome categories, respectively, while 3.7% (2/54) and 9.6% (5/52) of group LIFP and HIFP belonged to fair respectively, neither group belonged to poor. Satisfaction rates of patients in group LIFP and group HIFP were 98.1% (53/54) and 92.3% (48/52), respectively. The patients’ functional outcome grading and satisfaction rate in group LIFP were better than that in group HIFP. The VAS for low back and lower limb pain and the ODI improved significantly during the 12 months after surgery (all P < .001) in 2 groups. The VAS for low back and lower limb pain were no difference between two groups, however, the ODI of group LIFP was lower than that of group HIFP (P < .001). All patients achieved radiological fusion.The limited area decompression, intervertebral fusion, and pedicle screw fixation had a satisfactory effect on patients with DLSS with instability.