Objective To quantitatively evaluate the efficacy of a novel continuous irrigation sheath in improving the vision of flexible cystoscopy under hematuria using an in vitro bladder model. Methods An in vitro bladder model was designed for simulating flexible cystoscopy under hematuria. According to the presence of continuous hemorrhage the experiment was divided into the static experiment and the dynamic experiment. The experiment was divided into three groups according to three levels of the irrigation condition during flexible cystoscopy: no irrigation (Group 1), continuous irrigation without an outflow of water (Group 2), and continuous irrigation with an outflow of water (Group 3). The vision field of flexible cystoscopy and vision precision of flexible cystoscopy images were recorded at 30, 60, 90 and 120 s. Results The vision field and precision of flexible cystoscopy images were greatly different between the 3 groups in both the static and the dynamic experiments. Compared with Group 1, the vision field and precision were significantly improved in Group 2 and 3 in both the static and the dynamic experiments(P<0.01). The vision precision of Group 3 was significantly better than that in Group 2 in both the static and the dynamic experiments(P<0.05,P<0.01), and the vision field of Group 3 was also significantly better than that in Group 2 in the dynamic experiments (P<0.05). Conclusion The novel continuous irrigation sheath can effectively improve the vision field and precision of flexible cystoscopy.