The invention discloses an experimental device and a method for measuring rock mechanics parameters under action of ultrasonic wave and chemistry. The experimental device comprises a closed box body for placing a rock core to be tested, a rock mechanics testing machine for symmetrically loading the rock core to be tested from a left side and a right side through a left side loading shaft and a right side loading shaft, an ultrasonic transducer, an ultrasonic generator, a hydraumatic pressurizer, a vent valve arranged on the upper part of the closed box body, a pressure measurement unit, an ultrasonic power detector, an ultrasonic amplitude measuring instrument and a display unit. The experimental method comprises the following steps of: 1, preparing an experiment; 2, adding a chemical reagent; 3, carrying out ultrasonic treatment; and 4, booting loading and simultaneously carrying out rock mechanics parameter measurement in a loading process. The experimental device has a reasonable design, is convenient to install and arrange, has complete functions, is simple and convenient to use, has good use effect, and can be used for efficiently and quickly finishing a rock mechanics parameters measuring experiment of the rock core to be tested under the joint action of the ultrasonic wave and the chemical reagent.