An ejection-type safety intravenous needle, comprising a sheath, a hub, a cannula fixed on the hub, and a base, wherein a paddle is provided at the top of the base; an upper locking slot is formed in a top of the paddle; an upper sliding slot is formed below the upper locking slot in a penetrating manner; wherein said upper locking slot forms a first clamping structure; a lower sliding slot is formed in a side of the base in a penetrating manner, a lower locking slot is formed in a bottom of the lower sliding slot, wherein said lower locking slot forms a second clamping structure; wherein said upper sliding slot is arranged to be in communication with said lower sliding slot; an accommodation cavity is formed in the base; the hub is fixed in the accommodation cavity, and the cannula is exposed outside of the accommodation cavity; wherein, in an initial state the sheath is arranged to enclose the cannula, and a bottom of the sheath is arranged to be located in the accommodation cavity and provided with a first limiting structure; a second limiting structure, arranged to cooperate with the first limiting structure, is provided at a top of the accommodation cavity; an elastic element is provided in the accommodation cavity, and the elastic element abuts against a bottom end of the sheath; a third clamping structure, arranged to cooperate with the first clamping structure and the second clamping structure, is provided on the sheath; wherein the ejection-type safety intravenous needle is arranged such that the first clamping structure is connected to the third clamping structure in the initial state; under an action of a first external force, the third clamping structure is arranged to separate from the first clamping structure; and under an action of a second external force, the sheath is arranged to slide toward the elastic element until the third clamping structure connects with the second clamping structure, such that the cannula is exposed outside of the sheath; and wherein the first external force and the second external force are in different directions; wherein the third clamping structure is a snap lock provided on the sheath via a connecting seat. a paddle is provided at the top of the base; an upper locking slot is formed in a top of the paddle; an upper sliding slot is formed below the upper locking slot in a penetrating manner; wherein said upper locking slot forms a first clamping structure; a lower sliding slot is formed in a side of the base in a penetrating manner, a lower locking slot is formed in a bottom of the lower sliding slot, wherein said lower locking slot forms a second clamping structure; wherein said upper sliding slot is arranged to be in communication with said lower sliding slot; an accommodation cavity is formed in the base; the hub is fixed in the accommodation cavity, and the cannula is exposed outside of the accommodation cavity; wherein, in an initial state the sheath is arranged to enclose the cannula, and a bottom of the sheath is arranged to be located in the accommodation cavity and provided with a first limiting structure; a second limiting structure, arranged to cooperate with the first limiting structure, is provided at a top of the accommodation cavity; an elastic element is provided in the accommodation cavity, and the elastic element abuts against a bottom end of the sheath; a third clamping structure, arranged to cooperate with the first clamping structure and the second clamping structure, is provided on the sheath; wherein the ejection-type safety intravenous needle is arranged such that the first clamping structure is connected to the third clamping structure in the initial state; under an action of a first external force, the third clamping structure is arranged to separate from the first clamping structure; and under an action of a second external force, the sheath is arranged to slide toward the elastic element until the third clamping structure connects with the second clamping structure, such that the cannula is exposed outside of the sheath; and wherein the first external force and the second external force are in different directions; wherein the third clamping structure is a snap lock provided on the sheath via a connecting seat.