The invention discloses a construction method of a finite-element numerical model of a cave-type karst rock mass. The method includes: determining a mass karst rate, a range of a karst cave location, a distribution law of a karst cave size and a probability density function thereof according to engineering investigation and geophysical prospecting; on the basis of a Monte Carlo method, determining the karst cave location and determining the karst cave size to generate a karst cave, and testing, through the mass karst rate, whether a model meets requirements; and finally giving physical and mechanical parameters of rocks to a medium region, and giving physical and mechanical parameters of known inclusions in the karst cave to a karst cave region to obtain the finite-element numerical model of the to-be-analyzed cave-type karst rock mass. The cave-type karst rock mass model provided by the invention can flexibly describe distribution characteristics of a karst cave in practical engineering, and fully and accurately describe a karst rock mass with a karst cave distribution, has a stronger adaptability, and has a very important significance for evaluation of karst-area foundation, study of karst-area leakage laws, research of karst-area tunnel construction and the like.