An input system includes a keyboard, an emitting apparatus, and a receiving apparatus. The keyboard includes a number of signal pins. The emitting apparatus includes a number of keys, an encoder, and an emitter. When one of the keys is pressed, the encoder outputs a first signal and the emitter converts the first signal to a wireless signal. The receiving apparatus includes a decoder and a receiver. The decoder includes a number of outputs. The outputs of the decoder are connected to the signal pins of the keyboard respectively. The receiver receives the wireless signal of the emitter and reconverts the wireless signal to the first signal. The decoder decodes the first signal and the outputs of the decoder outputs a decoded signal. The decoded signal is used to control voltage level of the signal pins.