Objective To compare the efficacy of oral sulfate solution (OSS) and polyethylene glycol (PEG) electrolyte powder for colonoscopy bowel preparation. Methods A total of 283 randomized patients from 9 centers in China taking OSS (n=143) or PEG (n=140) using two‑day split bowel preparation regimen received colonoscopy and assessment. The primary index was the bowel preparation success rate [global Boston bowel preparation scale (BBPS)≥ 6 by independent assessment center]. Secondary indices included BBPS global and segmental scores, investigator satisfaction (5‑point Likert scale) with the quality of bowel preparation, patient satisfaction assessed by questionnaires, and patient tolerance assessed by Sharma scale. Compliance and safety were compared between the two groups. Results The bowel preparation success rates were 100.0% for OSS and 99.3% for PEG [adjusted difference 0.7% (95%CI: -5.3% - 6.7%), P<0.001 for non-inferiority]. The BBPS global score in OSS group was significantly higher than that in PEG group (8.1 VS 7.7, P<0.001). The segment BBPS scores were also higher in OSS group than those in PEG group for all 3 segments (right colon: 2.4 VS 2.3, P=0.002; transverse colon: 2.8 VS 2.7, P=0.018; left colon: 2.8 VS 2.7, P=0.007). Investigator Likert score in the OSS group was significantly higher than that in the PEG group (2.6 VS 2.3, P<0.001). There was no significant difference in compliance between OSS and PEG, except for the second dose (90.9% VS 82.6%, P=0.039). There was no significant difference in patient satisfaction, Sharma score or proportion of patients with tolerance-related symptoms between the two groups. Safety was comparable between the two groups, and all adverse events were mild to moderate. Conclusion OSS has comparable efficacy with PEG, with higher BBPS scores in all segments, better investigator satisfaction, better compliance in split dose, and comparable patient tolerance and safety.