This article presents a pen-like device that enables three-dimensional (3D) human-computer interaction. This device is based on a high-precision 3D ultrasonic (US) positioning method, which can achieve precise 3D positioning at millimeter level and six degrees of freedom (6DoF) within a working range of 4m × 1.5m × 1.5m The 3D -The electronic pen is positioned using a high-precision time-of-off (TOF) detection method based on dynamic thresholds and zero crossings Detection and an averaging method for multi-group positioning coordinates. During the 3D positioning process, correlation filtering is applied to process the received US signals and reject any spurious signals below 20kHz and above 60kHz. The positioning method can achieve high positioning accuracy without complex calculations. The attitude of the electronic pen is measured using inertial measurement units (IMU). To demonstrate the positioning accuracy of the proposed device. A total of 108 test positions are uniformly laid out on the work area, and static and dynamic positioning accuracy tests are carried out at all test positions. Experimental results show static and dynamic positioning errors of less than 0.35mm and less than 1.0mm, respectively, indicating high positioning accuracy. The proposed device can provide 6DoF and enable 3D writing.Therefore, the device can meet the usual needs of a 3D human-computer interaction interface.