Non-surgical methods such as percutaneous drainage are crucial for the treatment of patients with severe acute pancreatitis (SAP). However, there is still an ongoing debate regarding the optimal timing for abdominal paracentesis catheter placement and drainage.To explore the influence of different timing for abdominal paracentesis catheter placement and drainage in SAP complicated by intra-abdominal fluid accumulation.Using a retrospective approach, 184 cases of SAP complicated by intra-abdominal fluid accumulation were enrolled and categorized into three groups based on the timing of catheter placement: group A (catheter placement within 2 d of symptom onset, n = 89), group B (catheter placement between days 3 and 5 after symptom onset, n = 55), and group C (catheter placement between days 6 and 7 after symptom onset, n = 40). The differences in progression rate, mortality rate, and the number of cases with organ dysfunction were compared among the three groups.The progression rate of group A was significantly lower than those in groups B and groups C (2.25% vs 21.82% and 32.50%, P < 0.05). Further, the proportion of patients with at least one organ dysfunction in group A was significantly lower than those in groups B and groups C (41.57% vs 70.91% and 75.00%, P < 0.05). The mortality rates in group A, group B, and group C were similar (P > 0.05). At postoperative day 3, the levels of C-reactive protein (55.41 ± 19.32 mg/L vs 82.25 ± 20.41 mg/L and 88.65 ± 19.14 mg/L, P < 0.05), procalcitonin (1.36 ± 0.51 ng/mL vs 3.20 ± 0.97 ng/mL and 3.41 ± 0.98 ng/mL, P < 0.05), tumor necrosis factor-alpha (15.12 ± 6.63 pg/L vs 22.26 ± 9.96 pg/L and 23.39 ± 9.12 pg/L, P < 0.05), interleukin-6 (332.14 ± 90.16 ng/L vs 412.20 ± 88.50 ng/L and 420.08 ± 87.65ng/L, P < 0.05), interleukin-8 (415.54 ± 68.43 ng/L vs 505.80 ± 66.90 ng/L and 510.43 ± 68.23ng/L, P < 0.05) and serum amyloid A (270.06 ± 78.49 mg/L vs 344.41 ± 81.96 mg/L and 350.60 ± 80.42 mg/L, P < 0.05) were significantly lower in group A compared to those in groups B and group C. The length of hospital stay in group A was significantly lower than those in groups B and group C (24.50 ± 4.16 d vs 35.54 ± 6.62 d and 38.89 ± 7.10 d, P < 0.05). The hospitalization expenses in group A were also significantly lower than those in groups B and groups C [2.70 (1.20, 3.55) ten-thousand-yuan vs 5.50 (2.98, 7.12) ten-thousand-yuan and 6.00 (3.10, 8.05) ten-thousand-yuan, P < 0.05). The incidence of complications in group A was markedly lower than that in group C (5.62% vs 25.00%, P < 0.05), and similar to group B (P > 0.05).Percutaneous catheter drainage for the treatment of SAP complicated by intra-abdominal fluid accumulation is most effective when performed within 2 d of onset.©The Author(s) 2024. Published by Baishideng Publishing Group Inc. All rights reserved.