Introduction: The leadless pacemakers are implanted routinely under fluoroscopic image, yet the pacing sites and corresponding paced electrocardiography (ECG) remain unclear. This study was to determine the computed tomography (CT)-verified location of the leadless Micra™ pacemakers (Micra™) and ECG characteristics. Methods: 20 consecutive patients who met the pacemaker indications for bradycardia and underwent fluoroscopy assisted Micra TM implantation were enrolled. All subjects underwent a postoperative CT scan to determine the precise location of the Micra TM pacing tip. Paced 12-lead ECG characteristics were analysed and correlated with the Micra TM tip location. Results: In the nine partitions of fluoroscopic RAO images, 14 (70%) of 20 patients had the Micra TM tip in zone 5, 5 (25%) in zone 6 and 1 in zone 2. Reconstructed CT 3-D cardiac images found Micra TM tips mostly clustered near the anterior insertion between the RV septum and free wall with 12 cases at the insertion-septal side and 8 at the free-wall side. ECG morphological analysis found that the peak deviation index in ECG lead V1 was 0.402±0.061 for Micra TM tips at the insertion-septal side and 0.542±0.053 in the free-wall side (P <0.001 between two sides) and paced clumsy R wave was often observed for tips at the free-wall side though there was no difference in QRS duration between two sides. Conclusion. In routine Micra TM implantation, the pacing sites were often located in the anterior insertion region, either at the insertion-septal or free-wall side. The ventricular activation propagation likely depended on the pacing sites.