The present invention relates to a three-dimensional character substitution system and method, and provides a three-dimensional character substitution system and an operation method therefor, the three-dimensional character substitution system comprising: a modeling data storage unit that stores modeling data of a three-dimensional character; a character information reception unit that receives, from a content engine, character information including location, angle, and action information of a character on three-dimensional content; a character image generation unit that generates a two-dimensional image and depth information corresponding to each pixel of the two-dimensional image by controlling and rendering the modeling data of the three-dimensional character on the basis of the character information; and an image streaming unit that streams the generated two-dimensional image and depth information to the content engine.