A cylindrical battery and a battery pack are provided in embodiments of the application, which relates to the field of battery technology. The cylindrical battery includes a housing, a first end cover, a second end cover, a battery cell, and a pole post. The battery cell is accommodated in the housing, and the first end cover and the second end cover seal at ends of the housing, respectively. The pole post is connected with the battery cell and extended through the first end cover. The pole post is cylindrical, a diameter of the pole post is Φ1, and a diameter of the first end cover is Φ2, wherein Φ1/Φ2≤34%, and Φ1≥12mm.