A trial tachycardia (AT) originating from atrial appendage in 30% children with AT can often lead to tachycardia cardiomyopathy (TIC) resulted from the AT which is often incessant. Traditional radiofrequency ablation performed at atrial appendage usually is challenging with low success rate, high recurrence rate, and significant risk of pericardial tamponade. This article reports for the first time in China the successful treatment of a 10-year-old boy (34.5 kg) with AT originating from left atrial appendage combined with TIC using a novel contact force sensing pulsed field ablation (PFA) catheter. The clinical manifestations of the child were persistent palpitations with reduced heart function, which was detected by echocardiography with left ventricular end-diastolic diameter (LVEDD) of 48mm and left ventricular ejection fraction (LVEF) of 46%. The focal origin of the AT was confirmed at the distal position of left atrial appendage by the characteristics of 12-lead ECG and local activation time (LAT) map with 3-dimentional mapping system. During the procedure, the AT was successfully terminated using the novel PFA catheter with 1800V pulse-field energy at the contact force of about 20g and the total time of ablation application was 20s. The 1-month follow-up after the operation showed no recurrence of AT, significant improvement in cardiac function (LVEF 58%, LVEDD 44mm), and no complications occurred. This case report preliminarily demonstrated that novel contact force sensing PFA catheter provided a safe and effective strategy for minimally invasive treatment of refractory pediatric arrhythmia originating from atrial appendage by realizing three technical advantages: precise ablation in children's narrow cavity of atrial appendage, ultra-short ablation time and real-time contact force feedback. This technological breakthrough is of great significance for promoting the development of interventional treatment for complex arrhythmias in children.