Abstract： Objective To investigate the value of retrograde P wave morphology, RP interval and RPV1-RPE interval in the positioning of atrioventricular bypath at the onset of atrioventricular reentrant tachycardia with concealed pre-excitation syndrome.Methods One hundred and seventy-three cases with concealed pre-excitation syndrome underwent electrophysiology examination and radiofrequency ablation. Retrograde P wave morphology, RP interval and RPV1-RPE interval were monitored at the onset of atrioventricular reentrant tachycardia with concealed pre-excitation syndrome. Results The inversion of retrograde P wave in lead Ⅰand avL displayed in 75 cases (63.0%)in the left bypath. The erection of retrograde P wave in lead Ⅰand avL displayed in 46 cases (71.9%) in the right bypath. The inversion of retrograde P wave in lead Ⅱ, Ⅲ and avF displayed in 44 cases (100.0%) in LPS and RPS. The shortest interval of RPE was in RPS (92.6±13.1 ms) (P<0.01). The shortest interval of RPV1-RPE was in RPS (16.6±12.3 ms) (P<0.01).Conclusions On the basis of retrograde P wave morphology, RP interval and RPV1-RPE interval, more accurate positioning of atrioventricular bypath could be made in patients with concealed pre-excitation syndrome.