A new compsognathid dinosaur, Sinocalliopteryx gigas gen. et sp. nov., is erected based on a complete skeleton from the Early Cretaceous Yixian Formation of western Liaoning, northeastern China. It shares the features with Huaxiagnathus orientalis in having a manus as long as the humerus plus radius, very large and subequally long manual claws Ⅰ and Ⅱ, and reduced olecranon process on the ulna. But it differs from Huaxiagnathus orientalis in having the much large size, a very long maxillary process of premaxilla not extending the vertical level of the maxillary antorbital fossa, and the proportionally longer ulna and so on. Sinocalliopteryx gigas gen. et sp. nov. represents the largest species among the known compsognathid dinosaurs, suggesting the tendency of the body enlargement in compsognathids to some extent. The long filamentous integuments are attached to the whole body of this compsognathid, confirming that such integuments evolved firstly in the basal coelurosaurs. This new giant compsognathid was a fierce carnivorous theropod, as shown further by an incomplete dromaeosaurid leg inside its abdominal cavity.