Background: Local recurrence or distant metastasis after surgery is not rare for early-stage Non-Small Cell Lung Cancer (NSCLC) patients. Present clinicopathological parameters, such as TNM stages and pathological subtype, are limited effective, as Positive Predictive Value (PPV) is low while Negative Predictive Value (NPV) is high. In recent years, circulating tumor DNA (ctDNA) has emerged as a noninvasive method for early diagnosis, prognostic stratification, disease surveillance, and treatment response evaluation. We assessed whether circulating tumor DNA (ctDNA) detected by PEAC technology could be a biomarker for minimal residual disease (MRD) and prediction of postoperative relapse in early-stage NSCLC. Methods: We enrolled 132 NSCLC patients with EGFR, KRAS, NRAS, BRAF and PIK3CA mutations, and obtained plasma samples at five perioperative time points (before surgery, 3-7 days, 6-months, 12-months and 18-months after surgery). Using PEAC technology, somatic mutations in plasma samples were identified and utilized for ctDNA-based MRD analysis. Clinical follow-ups were collected. Results: Our data showed that 32.0% (8 of 25) of patients with positive preoperative ctDNA experienced postoperative relapse, compared with 7.2% (6 of 83) in ctDNA negative patients, demonstrating that preoperative ctDNA status is an effective prognosis factor for NSCLC. In time point of 3-7 days after surgery, plasma samples were obtained from 47 patients, of which 33.3% (2 of 6) with positive ctDNA experienced postoperative relapse, while only 4.9% (2 of 41) in ctDNA negative patients. The result suggests that ctDNA positive in plasma samples of 3-7 days after surgery might be a strong biomarker for MRD detection and relapse prediction. For ctDNA surveillance, plasma samples from 6-months, 12-months and 18-months after surgery were collected and detected. At any one of the three tests ctDNA is positive, 20.0% (8 of 40) patients experienced clinical relapse, while 5.1% (3 of 59) patients with ctDNA negative status at all times relapse. A total of 14 recurrence events had occurred, ctDNA positivity precedes radiological recurrence by a median of 150.5 days (90.5 – 182, P = 0.006). Conclusions: Perioperative ctDNA analysis using PEAC technology is effective in early detection of MRD and relapse prediction, and hence could benefit NSCLC patient management in clinical settings. Clinical trial information: NCT03465241.