Objective A rat model of pulmonary fibrosis was constructed using a single or two intratracheal drops of bleomycin (BLM) and the modeling rate and stability of the two modeling modalities were compared. Methods A total of 150 specific pathogen-free SD rats were divided randomly into blank control (control), single intratracheal drop of bleomycin (BLM-S), and two intratracheal drops of bleomycin (BLM-M) groups. Rats in the BLM-S group received a single dose of 3 mg/kg BLM by noninvasive intratracheal instillation, and rats in BLM-M group received 3 mg/kg BLM on day 1 and BLM 2 mg/kg on day 14. Rats in the control group were given intratracheal instillation of 0.9% sodium chloride (1 mL/kg). The rats were euthanized on days 28, 42, 56, and 84 after modelling, respectively. Deep inspiratory capacity (IC), vital capacity (VC), static lung compliance (Cchord), and dynamic lung complication (Cdyn) were measured in all rats. Pathological changes in lung tissue were observed, and the extent of alveolitis and fibrosis was graded. Collagen-III (COL-III) expression in rat lung tissue was detected by immunohistochemistry. Results (1)The survival rates in the control, BLM-S, and BLM-M groups were 100%, 80%, and 66%, respectively. Rats in the BLM-S and BLM-M groups had significantly lower body weights on days 14 ~ 42 compared with the control group (P<0.05, P<0.01), and rats in the BLM-M group had significantly lower body weight on days 28 ~ 42 than rats in the control and BLM-S groups (P<0.05, P<0.01). (2)Regarding lung function, IC, VC, Cchord, and Cdyn were all markedly decreased in the BLM-S group compared with the control group (P<0.05, P<0.01) and IC, VC, and Cchord were significantly decreased in the BLM-M group (P<0.05, P<0.01) on day 28. IC, VC, and Cchord were significantly decreased in rats in the BLM-S group on day 42 (P<0.05, P<0.01), and were also significantly decreased in rats in the BLM-M group on days 42 ~ 84 (P<0.05, P<0.01). (3)In terms of lung pathology, inflammatory infiltration and fibrous cords appeared in the BLM-S group from days 28 ~ 84 and then gradually decreased (P<0.05, P<0.01), while fibrosis and alveolitis were relatively stable in the BLM-M group (P<0.05, P<0.01). (4)COL-III expression levels in lung tissue were significantly higher in rats in the BLM-S and BLM-M groups compared with the control group (P<0.05, P<0.01), and the COL-Ⅲ content in the BLM-S group was significantly lower at 42 ~ 84 days than at 28 days (P<0.05). Conclusions Both method are capable of effectively creating pulmonary fibrosis models. The single-dose approach is straightforward, has a lower death rate, and the degree of fibrosis is clearly visible by day 28, but progressively recovers after 42 days. In contrast, the two-dose instillation model has a greater success rate and better stability, with over half the rats still exhibiting visible fibrosis on day 84.