The invention relates to the field of simulation, in particular to a plane fissure grouting quasi-three-dimensional simulation method and system based on a finite volume method. The plane fissure grouting quasi-three-dimensional simulation method based on a finite volume method comprises the steps: S10, conducting pretreatment; S20, initializing a flow field; S30, calculating material characteristic parameters; S40, carrying out iterative solution on the flow field; S50, updating a VOF function value; and S60, outputting a result; and S70, judging whether a preset number of operations are executed or not, and if so, ending the operations; and if not, executing the step S30. According to the plane fissure grouting quasi-three-dimensional simulation method, a plane fissure grouting three-dimensional problem is converted into a two-dimensional problem considering the fissure opening degree to be solved, and the scale of a numerical model can be remarkably reduced, and computing resourcesare saved, and computing time is shortened, and high solving precision is achieved.