Objective：To investigate the effect of telmisartan on Ras/Raf/ERK1/2 signal pathway in rats with myocardial hypertrophy. Methods：Totally 30 rats were randomly divided into 3 groups including control group，model group and intervention group. Each group has 10 rats. Hypodermic injection of normal saline was applied in control group；hypodermic injection of isoproterenol was ap－plied in model group；hypodermic injection of isoproterenol and telmisartan was applied in intervention group. Myocardial index and pathological detections were performed. RT-PCR assay was used to detect ANP mRNA expression. After the model was successfully made，rats’ left cardiac tissues were collected and p-Raf protein and p-ERK1/2 protein expression was detected by immunohis－tochemistry. Results：Average integral optical density in p-Raf positive area was the highest in model group（P=0.000） followed by intervention group and control group（P=0.041，P=0.031）. Average integral optical density in p-ERK1/2 positive area was the highest in model group（P=0.000） followed by intervention group and control group（P=0.0039，P=0.023）. Conclusions：Telmisartan resists my－ocardial hypertrophy since it can reduce expressions of Raf protein and ERK1/2 and inhibit the activation of Raf/MEK/ERK signal pathway