BACKGROUND: Colonic transendoscopic enteral tubing (TET) requires double cecal intubation, raising a common concern of how to save cecal intubation time and make the tube stable. We hypothesized that cap-assisted colonoscopy (CC) might reduce the second cecal intubation time and bring potential benefits during the TET procedure. AIM: To investigate if CC can decrease the second cecal intubation time compared with regular colonoscopy (RC). METHODS: This prospective multicenter, randomized controlled trial was performed at four centers. Subjects ≥ 7 years needing colonic TET were recruited from August 2018 to January 2020. All subjects were randomly assigned to two groups. The primary outcome was the second cecal intubation time. Secondary outcomes included success rate, insertion pain score, single clip fixation time, purpose and retention time of TET tube, length of TET tube inserted into the colon, and all procedure-related (serious) adverse events. RESULTS: A total of 331 subjects were randomized to the RC ( = 165) or CC ( = 166) group. The median time of the second cecal intubation was significantly shorter for CC than RC (2.2 min 2.8 min, < 0.001). In patients with constipation, the median time of second cecal intubation in the CC group ( = 50) was shorter than that in the RC group ( = 43) (2.6 min 3.8 min, = 0.004). However, no difference was observed in the CC ( = 42) and RC ( = 46) groups of ulcerative colitis patients (2.0 min 2.5 min, = 0.152). The insertion pain score during the procedure in CC ( = 14) was lower than that in RC ( = 19) in unsedated colonoscopy (3.8 ± 1.7 5.4 ± 1.9; = 0.015). Multivariate analysis revealed that only CC (odds ratio [OR]: 2.250, 95% confidence interval [CI]: 1.161-4.360; = 0.016) was an independent factor affecting the second cecal intubation time in difficult colonoscopy. CC did not affect the colonic TET tube's retention time and length of the tube inserted into the colon. Moreover, multivariate analysis found that only endoscopic clip number (OR: 2.201, 95%CI: 1.541-3.143; < 0.001) was an independent factor affecting the retention time. Multiple regression analysis showed that height (OR: 1.144, 95%CI: 1.027-1.275; = 0.014) was the only independent factor influencing the length of TET tube inserted into the colon in adults. CONCLUSION: CC for colonic TET procedure is a safe and less painful technique, which can reduce cecal intubation time.