Objective To explore the application value and effect of 24h Holter

3D Scattergram and Time scatter diagram in the diagnosis of atrial fibrillation with secondary atrioventricular block. Methods One hundred and eightpatients with atrial fibrillation who were treated in Zhuhai Hospital of Guangdong Provincial Hospital of Traditional Chinese Medicine from September 2016 to December 2019 were divided into observation group including patients with secondary atrioventricular block（n=30） and control group including patients without secondary atrioventricular block（n=78）. Twenty-four-hour ambulatory electrocardiogram monitor was completed in both groups after admission. The characteristics of 24h ambulatory ECG

3D scattergram and time scatter diagram in the diagnosis of atrial fibrillation with secondary atrioventricular block were analyzed. Results The results of 24-hour ambulatory electrocardiogram showed that the average ventricular rate of the observation group was lower than that of the control group（p<0.05）

and there was no significant difference between the observation group and the control group in the average of the long RR period over 2 seconds（p>0.05）. The 3D scattergram of the observation group showed obvious characteristics of "sweet tube shape"

and it shows like a regular heagon from the X-Y-Z observation. Two circles can be used to estimate the occurrence matrix of the secondary atrioventricular block

and the time scattergram can see the occurrence time of the block. The 3D scattergram was similar to the "top shape" or "bouquet shape" of the triangular body

and it was similar to a triangle when observed from X-Y-Z in the control group. Conclusions Twenty-four-hour ambulatory electrocardiogram can reflect the heart rate changes of patients with atrial fibrillation

and the combination of 3D scattergram and time scatter plot can improve the diagnostic efficiency and accuracy of atrial fibrillation with secondary atrioventricular block

which has better clinical application value.