Background: Although many studies have confirmed the correlation between inflammation-based or nutritional markers and postoperative complications in patients undergoing colorectal cancer surgery, their correlation after undergoing pancreaticoduodenectomy (PD) remains unclear. Methods: We retrospectively reviewed the clinical data of patients who underwent PD in Beijing Friendship hospital between 2018 and 2020. Univariate analysis, multivariate analysis, and receiver operating characteristic curve (ROC) were performed. We assessed the preoperative modified Glasgow Prognostic Score (mGPS), C-reactive protein/albumin ratio (CAR), C-reactive protein (CRP), postoperative Glasgow Prognostic Score (poGPS), CRP on postoperative day 3 (POD3) and CAR on POD3. The optimal cut-off values were determined by performing logistic regression analysis. Results: Of the 172 patients who underwent PD, 74 (43.0%) developed complications, of whom 27 (15.7%) had clinically relevant postoperative pancreatic fistulas (CR-POPF) and 36 (20.9%) had positive drainage fluid cultures. Elevated levels of preoperative mGPS (P<0.001), poGPS (P<0.001), CRP (P<0.001) and CAR on POD3 were associated with postoperative complications. CRP on POD3 (OR=1.028, 95% CI=1.017-1.039, P<0.001) was an independent risk factor associated with postoperative complications in both univariate and multivariate analyses. CAR on POD 3 showed the largest area under the curve (AUC=0.883, P<0.001). Compared with CAR<4.86, CAR =4.86 on POD3 was associated with a higher probability of complications (85.5% vs 14.6%, P<0.001), especially CR-POPF (33.3% vs 4.9%, P<0.001), intra-abdominal infection (36.2% vs 10.7%, P<0.001) with a positive drainage fluid culture. Conclusion: CAR, an inflammatory response-based marker, can effectively predict early postoperative complications in patients undergone PD.