Objective To investigate the characteristics of arrhythmia and heart rate variability in the patients with acute myocardial infarction (AMI) at different sites. Methods A retrospective study was carried out on the AMI patients admitted to our hospital from January 2015 to June 2016. According to the result of electrocardiogram, they were divided into non-ST-segment elevation myocardial infarction (NSTEMI) group, inferior-wall group, and anterior-wall group. The dynamic electrocardiogram data during hospitalization was analyzed, and the arrhythmia and heart rate variability were compared among the groups. Results A total of 239 patients with AMI were enrolled. There were no significant differences in the incidences of frequent ventricular premature beats (VPB), Lown’s degree ≥3-stage VPB and atrial arrhythmia among the 3 groups (P>0.05). However, the NSTEMI and inferior-wall groups had obviously higher incidence of bradyarrhythmia than the anterior-wall group (P<0.05). The standard deviation of all normal R-R intervals (SDNN), standard deviation of the average normal RR intervals(SDANN) and average of the standard deviations of normal RR intervals (ASDNN) were notably lower in the anterior-wall group than the other 2 groups (P<0.05). Conclusion Compared with anterior-wall AMI patients, NSTEMI and inferior-wall patients have higher incidence of bradyarrhythmia and reduced variability of heart rate.