The application discloses a cap integrally formed by EVA injection molding and an injection mold thereof. The cap integrally formed by EVA material comprises a headband part, a connecting part and a brim part, the connecting part is arranged between the headband part and the brim part, the thickness of the headband part gradually decreases with the distance from the connecting part, the thickness of the brim part gradually decreases with the distance from the connecting part, and the thickness of the connecting part is greater than the thickness of the headband part and the brim part. Through the integrally formed setting of the cap, the thickness of the headband part gradually increases from the edge to the connecting part, and the thickness of the brim part also gradually increases from the edge to the connecting part, so that the supporting force of the cap is improved, the stability of the cap structure is better, and the overall weight of the cap can be controlled by reducing the edge thickness. In addition, the cap is made of EVA material, so that the performance defects of the cap, such as insufficient flexibility, easy deformation and poor resilience, can be improved, and the cleaning of the cap is facilitated.