An intra-cardiac myocardial resection device, comprising an outer protective sleeve (1) and an inner scalpel sleeve (2). The upper sidewall of the outer protective sleeve (1) is provided with a resection window, and a top edge of the resection window is provided with a downward hook (10)； the sidewall of the outer protective sleeve (1) is provided with an axial sliding groove (4). The inner scalpel sleeve (2) is mounted in the outer protective sleeve (1), and the upper end of the inner scalpel sleeve (2) is provided with an annular blade (11) having an upward edge. The sidewall of the inner scalpel sleeve (2) is provided with a hollow operation handle (6), and the hollow operation handle (6) extends out of the sliding groove (4). Surgery can be performed by using such an intra-cardiac myocardial resection device, without extracorporeal circulation, so that the surgical time is significantly shortened, the trauma of a traditional median thoracotomy is reduced, and complications related to extracorporeal circulation are avoided. More importantly, during the surgery, a resection extent and a resection effect can be monitored and evaluated in real time in a heart beating state, complications such as ventricular septal rupture and an insufficient resection extent are avoided, and the surgical treatment effect for such patients is improved.L'invention concerne un dispositif de résection myocardique intracardiaque, comprenant un manchon de protection externe (1) et un manchon de scalpel interne (2). La paroi latérale supérieure du manchon de protection externe (1) est pourvue d'une fenêtre de résection et un bord supérieur de la fenêtre de résection est pourvu d'un crochet vers le bas (10)； la paroi latérale du manchon de protection externe (1) est pourvue d'une rainure de coulissement axiale (4). Le manchon de scalpel interne (2) est monté dans le manchon de protection externe (1) et l'extrémité supérieure du manchon de scalpel interne (2) est pourvue d'une lame annulaire
