A pressing head structure (100) for testing key durability includes a pressing mechanism (10), a rubber head (40), a connecting mechanism (20) and a balance mechanism (30). The pressing mechanism includes a sliding rod (12) and a first spring (16). The first spring is placed over the sliding rod. The connecting mechanism connects the pressing mechanism and the rubber head. The balance mechanism is rotatably fixed to the connecting mechanism. The balance mechanism engages with the pressing mechanism. When the sliding rod moves down, the first spring and the balance mechanism together supply an unaltered resultant resistance in the moving direction of the sliding rod.