Posterolateral fusion (PLIF) with autogenous bone graft is considered the gold standard for lumbar spinal fusion. However, the fusion rate and effectiveness of locally derived corticocancellous structural autograft vs. morcellized fragments autograft for lumbar PLIF, following single level lumbar laminectomy in patients with symptomatic lumbar spinal stenosis, remain unknown. Thus, the present study aimed to compare the fusion rates of corticocancellous structural autograft and morcellized fragments autograft for the treatment of lumbar PLIF. A randomized self-controlled trial was conducted comprising of 135 patients with symptomatic lumbar spinal stenosis, single level lumbar laminectomy and PLIF, with corticocancellous structural autograft (group 1) and morcellized fragments autograft (group 2). The primary outcome measurements included the PLIF rate, radio density and dimensions of PLIF mass on both sides, which were assessed via X-rays at 3, 6 and 12 months, postoperatively. Furthermore, changes in bilateral bone fusion bridges were assessed via CT scanning, according to the Lenke CT fusion measurement criteria. The follow-up period lasted for 1 year (period between January 2013 and January 2018). Of the 135 patients were initially included in the present study, 7 patients were lost during the following up process. Therefore, data from 128 patents were eventually assessed, 94.8% of surgical levels were observed at Honghui Hospital. According to the Lenke CT fusion measurement criteria, the overall unilateral fusion rates were 71.9% (92/128) in group 1 and 31.3% (40/128) in group 2. Furthermore, both the radio density and dimensions of PLIF mass significantly decreased at a faster rate in group 1 compared with group 2 (radio density; 0.65-0.49 vs. 0.63-0.61; P<0.05 and PLIF mass; 398-124 vs. 376-223 mm²; P<0.05). The CT scan results demonstrated that the mean volume of bone graft was significantly greater in group 1 compared with group 2, at 12 months postoperatively (1.47 vs. 1 cm³; P<0.05). Taken together, the results of the present study suggested that corticocancellous structural autograft is more effective for earlier resorption and stabilization of patients undergoing PLIF, compared with morcellized fragments autograft.