The hybrid beamforming system based on phase shifters and antenna array can achieve excellent communication performance by the high bandwidth and mutually orthogonal beams of the millimeter wave (mmWave). However, existing beamforming techniques have considerable high computational complexity. And the phase shifter arrays in the mmWave system are costly and are not suitable for the internet of thing (IoT) devices that can be deployed in large quantities. This paper proposes a new low-cost energy-efficient mmWave communication system based on beam modulation, which utilizes the attenuation characteristics of different clusters of the channel to achieve modulation. The IoT nodes in the proposed system remove the antenna array and phase shifter network and achieve communication without signal modulation, channel estimation, beam searching and beam alignment. The experiment shows that the proposed system is superior to the existing hybrid mmWave communication system in terms of cost and energy efficiency.