Desminopathy is a rare heritable cardiac and skeletal muscle disease caused by variants in the DES gene, which encodes the primary muscle-specific intermediate filament protein, known as desmin. Childhood-onset is commonly associated with severe early-onset myopathy and early death. Here, we reported an 11-year-old Chinese girl presenting with complete atrioventricular block and cardiomyopathy, without skeletal muscle involvement. Genetic analysis identified a de novo variant (c.152C > T/p.Ser51Phe) in the DES gene.