The invention provides a fast angle measuring instrument, which is suitable for single-person operation and can be used for fast measuring the angle. The fast angle measuring instrument comprises a front casing, a back casing, a horizontal infrared distance measuring module, a vertical infrared distance measuring module, a display screen, an integrated circuit board, a power supply, a horizontal instrument sensor and a press key, wherein the horizontal infrared distance measuring module is fixedly arranged on the front casing; the vertical infrared distance measuring module is fixedly bonded on the front casing and the top surface of the front casing; the display screen is fixedly arranged on the front casing; the press key and the horizontal instrument sensor are fixedly arranged on the front casing; the integrated circuit board and the power supply are arranged on the back casing; the front casing and the back casing are mutually buckled through a clamp buckle and are fixedly connected through screws; the horizontal infrared distance measuring module, the vertical infrared distance measuring module, the display screen, the power supply, the horizontal instrument sensor and the press key are respectively connected with the integrated circuit board through conducting wires; the inclined surface angle fast measurement can be realized, so that the conventional multi-person measurement calculation work is changed into one-person fast measurement result obtaining work; the measuring efficiency is improved; the accuracy is also improved.