Objective To compare the ECG features during sinus rhythm between arrhythmogenic right ventricular cardiomyopathy（ARVC） and idiopathic right ventricular outflow tract ventricular tachycardia（RVOT） in China. Methods The ECG features during sinus rhythm before treatment were reviewed in 21 patients diagnosed with ARVC in People’s Hospital of Peking University from 2008 to 2018 and 31 patients diagnosed with idiopathic right ventricular outflow tract ventricular tachycardia（RVOT） who also had radio frequency ablation from 2008 to2011. Results The mean duration of QRS（QRSd） of V1 lead in ARVC group was longer than that of RVOT（118.6±23.8 ms vs. 98.5±20.6 ms

p<0.05）. The difference of QRSd between lead V1 and lead I in ARVC was greater than that of RVOT（19.9±8.2 ms vs. 10.0±8.6 ms

p<0.05）. The difference of QRSd between lead V1 and lead V6 in ARVC was also greater than that of RVOT（20.5±9.7 ms vs. 7.3±8.2 ms

p<0.05）. The ratio of QRSd of lead V1 to lead V6 in ARVC was greater than that of RVOT（1.22±0.11 vs. 1.08±0.096

p<0.05）. Right precordial Epsilon waves were presented in 33.3% of ARVC patients

and 3.2% of RVOT patients

p<0.05. Right precordial fragmented QRS were presented in 42.9% of ARVC patients

while 12.9% of RVOT patients

p<0.001. Either right precordial Epsilon waves or fragmented QRS were presented in 71.4% of ARVC patients

while 16.1% of RVOT patients

p<0.001. Localized right precordial QRS prolongation was presented in 61.9% of ARVC patients

while 12.9% of RVOT patients

p<0.001.85.7% of the ARVC patients were positive with one of the above three presentation of the right precordial abnormal features

while 16.1% of RVOT patients

p<0.001. The morphology of QRS of lead V1 was different between two group.57.1% of ARVC patients presented r Sr（R） type

33.3% presented r S type; while 83.9% of RVOT patients presented r S type

12.9% presented r Sr（R） type. Conclusions Patients with right precordial Epsilon waves or fragmented QRS or localized right precordial QRS prolongation were more frequent in ARVC group than in RVOT group. The features of sinus rhythm ECG may have high value in differential diagnosis between ARVD and RVOT.