In this study, we aimed to explore the demographic and clinical factors that could determine the short- and long-term complete pain relief (CPR) in adult patients with primary trigeminal neuralgia (PTN) after microvascular decompression (MVD) to guide clinical practice. This single-center retrospective study included 200 adult patients with PTN who underwent MVD as their initial neurosurgical procedure in the Department of Neurosurgery at the Second Affiliated Hospital of Harbin Medical University from January 2017 to December 2019 and completed a 3-year post-surgery follow-up. Pain relief of local patients at different time points after sufficient decompression of TN during MVD was evaluated by outpatient follow-up, whereas those of local cases who could not return to outpatient follow-up or non-local cases were assessed through telephone or WeChat.The type of conflicting vessels and the compression degree of TN at various time points after MVD were the related factors to CPR in logistic regression analysis, with the former having the greatest impact. The areas under the ROC curve of CPR at different time points after MVD were 0.937, 0.874, 0.879, 0.864, and 0.869, respectively. In summary, the compression degree of TN and the type of conflicting vessels could determine the short- and long-term CPR in adult patients with PTN after sufficient decompression of TN during MVD, which allowed better characterization of potential candidates suitable for MVD and contributed to optimizing the planning of MVD.