The invention discloses a low-frequency wave transmitting device, which comprises a low-frequency wave transmitter and an attitude control device. The attitude control device comprises an attitude control shell and high-density heavy liquid, and the low-frequency wave transmitter is arranged in an inner cavity of the attitude control shell and floats in the high-density heavy liquid. The inventiondiscloses a wireless displacement sensing device using the low-frequency wave transmitting device. The wireless displacement sensing device comprises the low-frequency wave transmitting device and anelectromagnetic wave receiver; and the electromagnetic wave receiver is composed of a receiving-end space orthogonal coil and a voltage measurement device, and the electromagnetic wave receiver receives an electromagnetic wave signal emitted by the low-frequency wave transmitter and converts the electromagnetic wave signal into the voltage so as to obtain position variation between the low-frequency wave transmitter and the electromagnetic wave receiver. The wireless displacement sensing device is used for monitoring the displacement variation of objects buried in a soil body or submerged inwater, and is reasonable in structure, the problem that electromagnetic waves are prone to being blocked by large obstructions is solved, and the accuracy of object displacement monitoring is improved.