Objective To observe the plastic changes of pain threshold in myocardial infarction rats, and to investigate the effects of nicotine on visceral pain and whether it has protective effects on ischemic myocardium. Methods Thirty healthy male Sprague-Dawley rats weighing 180 to 200 g were selected and divided into a sham surgical group, model group, or nicotine treatment group at random. The changes of electrocardiogram (ECG), pain threshold ( thermal pain threshold PWL, mechanical pain threshold PWT), left ventricular pressure amplitude, cardiac body mass index, and creatine kinase isoenzyme (CK-MB) were observed in all groups of rats. Results Upon comparing the model group with the sham surgical group, the mechanical pain threshold decreased and the thermal pain threshold became larger in the former group (both P<0. 05), while the plasma CK-MB activity, cardiac body mass index, and left ventricular pressure significantly increased (all P<0. 05). In addition, when the nicotine treatment group was compared with the model group, the mechanical pain threshold increased in the former group, while the thermal pain threshold decreased, as did the plasma CK-MB activity, cardiac body mass index, and left ventricular pressure (all P<0. 05). Conclusions Nicotine can relieve myocardial ischemia symptoms and visceral pain caused by ischemia in rats with myocardial infarction. Its mechanism may be related to activation of the cholinergic anti-inflammatory pathway. Therefore, it can improve the pain and protect the heart of rats.