The outcomes of non-small cell lung cancer surgery are influenced by the quality of lymphadenectomy. This study aimed to evaluate the impact of different energy devices on lymphadenectomy quality and identify additional influencing factors. This secondary analysis of the prospective randomized trial data (clinicaltrials.gov: NCT03125798) compared patients who underwent thoracoscopic lobectomy with the LigaSure device (study group,n= 96) and monopolar device (control group,n= 94). The primary endpoint was the lobe-specific mediastinal lymphadenectomy. Lobe-specific mediastinal lymphadenectomy criteria were met in 60.4% and 38.3% of patients in the study and control groups, respectively (p =0.002). In addition, in the study group, the median number of mediastinal lymph node stations removed was higher (4 vs. 3,p =0.017), and complete resection was more often achieved (91.7% vs. 80.9%,p =0.030). Logistic regression analysis indicated that lymphadenectomy quality was positively associated with the use of the LigaSure device (OR, 2.729; 95% CI, 1.446 to 5.152;p =0.002) and female sex (OR, 2.012; 95% CI, 1.058 to 3.829;p =0.033), but negatively associated with a higher Charlson Comorbidity Index (OR, 0.781; 95% CI, 0.620 to 0.986;p =0.037), left lower lobectomy (OR, 0.263; 95% CI, 0.096 to 0.726;p =0.010) and middle lobectomy (OR, 0.136; 95% CI, 0.031 to 0.606,p =0.009). This study found that using the LigaSure device can improve the quality of lymphadenectomy in lung cancer patients and also identified other factors that affect the quality of lymphadenectomy. These findings contribute to improving lung cancer surgical treatment outcomes and provide valuable insights for clinical practice.