A key preloading structure including a base, a set of switches and a set of keys is provided. The set of switches is arranged on the base. The set of keys has a rotating shaft and two actuators. The rotating shaft is assembled on the base. One end of each actuator is fixedly connected to the rotating shaft, and another end is disposed on a switch of the set of switches. Each of the two actuators preloads the set of switches with a force less than a triggering force for starting the set of switches.