The invention discloses an acoustic wave tide measurement instrument. The acoustic wave tide measurement instrument comprises an underwater part and an overground part, wherein the underwater part comprises an underwater bracket and a watertight case mounted on the underwater bracket, and the overground part is an upper computer; an acoustic energy converter array is distributed at the top of thewatertight case, and a pressure sensor and a temperature sensor are mounted on the side surface of the acoustic energy converter array and on the surface of the watertight case; and a signal processing board and a battery are arranged in the watertight case, and a three-dimensional electronic compass and a memory card are mounted on the signal processing board. The invention simultaneously discloses an acoustic wave tide measurement method. The measurement method comprises the following steps: data collection, data processing and calculation of high-low tides and wave characteristic values. The acoustic wave tide measurement instrument can be used for simultaneously measuring wave height, wave period, wave direction and tide level and has the functions of automatically finishing the collection, processing, storage, formulation and submitting of files, remote transmission and user service in an all-weather manner, is strong in universality, provides measurement data with high accuracy and is applicable to occasions of coastal ocean stations, wharfs, large-scale ocean engineering and the like.