The disclosure relates to an LED lamp and an optical lens thereof. The optical lens includes a dome structure and a protrusion structure, the dome structure has an external surface, the protrusion structure is disposed on the external surface of the dome structure; the protrusion structure has a first optical surface and a first optical side connected with the first optical surface, the first optical surface and the external surface are connected to form a first boundary, the first optical side and the first boundary are inclined. The disclosure further provides an LED lamp. The LED lamp and the optical lens thereof above can improve optical efficiency.