Objective To understand the cardiac function of patients with tumor chemotherapy

and to explore the clinical significance of dynamic electrocardiogram in patients with tumor chemotherapy. Methods fifty-six cases of cancer chemotherapy patients and 56 cases of healthy people（control group） were selected for dynamic electrocardiogram examination. The heart rate variability

including the incidence of heart rate variability reduction

the standard deviation of 24 h normal RR interval（SDNN）

the standard deviation of average RR interval every 5 minutes（SDANN）

and the average of standard deviation of normal cardiac cycle every 5 minutes were analyzed（ASDNN）; the incidence of arrhythmia; the incidence of ST-T changes. Results The indexes of SDNN

SDANN and ASDNN in the tumor group were significantly lower than those in the control group（p<0.05）; the incidence of decreased heart rate variability

arrhythmia and ST-T changes in the tumor group were significantly higher than those in the control group（p<0.05）; the incidence of various types of arrhythmias were also significantly different（p<0.05）.Conclusions Dynamic electrocardiogram examination is convenient

fast and noninvasive. It can be applied to cancer patients to understand their ECG activity

analyze heart rate variability

and understand whether there are arrhythmias and myocardial ischemia. It can provide important cardiovascular risk factors assessment data for oncologists

and help to identify high-risk patients and screen out subclinical patients with cardiotoxicity

So as to reduce the incidence of cardiotoxicity.