Abstract: The present invention provides a plate-fin heat exchanger core and a fin structure thereof. The plate-fin heat exchanger core includes: a plurality of partition plates and a fin, where the fin is supported and fixed between two adjacent partition plates; the two adjacent partition plates are sealed to form a fluid channel unit; the fluid channel unit forms a plurality of heat exchange channels for a medium to flow between the adjacent partition plates; the fin is provided with a plurality of dimples/protrusions; the dimple/protrusion is provided with a perforated hole to form a perforated dimple/protrusion. The fin increases the heat exchange area, and the dimple/protrusion structure improves the pressure-bearing capacity of the plate-fin structure and improves fluid turbulence, thinning a flow boundary layer and a hot boundary layer.