Resin impregnation process is one of the most important steps in liquid composite molding for producing a fiber-reinforced composite. Resin flow through fiber preforms has a great effect on both properties of final product and process development. Factors related to the flow of resin are injection pressure, viscosity of the resin and permeability of the fiber mat. Permeability is the parameter to describe the diffusion of liquid and gas to the porous material such as fiber mat. Permeability is mainly affected by the structural factors of fiber preform such as fiber volume fraction and structure of textile pattern. Conventional methods for measuring the permeability are unsaturated or saturated unidirectional flow, unsaturated radial flow method, and so on. However, these methods need an independent experiment on each fiber volume fraction, which has error factors in injection pressure, fiber mat dimension, and calculating image analysis. In this study, the system which can continuously measure the permeability with the various fiber volume fractions was proposed. This system is to measure the permeability with varying the mold position in the vertical direction, by which the fiber volume fraction can be changed continuously. This system can minimize the time of experiment and errors from each measurement batch. The measured value was compared with the value measured by conventional method to verify the new continuous measurement technique. Keywords: Permeability, Fiber volume fraction, Continuous measurement