Objective Current research and treatments for the pathogenesis of chronic heart failure (CHF) are limited. In order to better study its pathogenesis, this paper optimized the preparation method of isoproterenol (ISO)?induced chronic heart failure rat model. Methods SD male rats were divided into 4 groups, and rats in model A were injected with ISO 5 mg/ (kg·d) continuously for 10 days; rats in model B were injected with ISO 2.5 mg/ (kg·d) on the first 3 days and 5 mg/ (kg·d) on the last 9 days; rats in model C were given 15 mg/ kg of pentobarbital sodium on day 1 and ISO 1?? 25 mg/ kg on day 2 and 3, and 2.5 mg/ (kg·d) on day 2 and 3, and 5 mg/ (kg·d) on the last 9 days, with 30 min interval between 2 injections per day from day 2. The control group was given equal amounts of saline. The successful establishment of the model was verified by echocardiography, pathology testing and fluorescence quantitative PCR. Results Mortality rates were 80%, 60%, and 40% in model groups A, B, and C, respectively. Compared with the control group, the left ventricular short axis shortening and ejection fraction were significantly lower in model group C (P<0.001). Rats in group C had disturbed myocardial cell arrangement, significantly increased collagen type Ⅰ and Ⅲ expression (P< 0.05), and significantly upregulated expression levels of fibrosis indexes COL1A1, COL3A1, FN1 and ACTA2 mRNA (P< 0.05), while the levels of serum N?terminal pro?B type natriuretic peptide (NT?pro BNP) and triglycerides were significantly increased (P< 0.05). Conclusions Injecting anesthetics to keep the rats in a semi?conscious state, increasing the daily injection dose and decreasing the single injection dose in a gradient can reduce the mortality rate, which can provide a new idea and a new approach for establishing a CHF rat model.