The invention discloses a method for testing wettability of fibers. The method comprises the following steps: (1) scissoring a heat-shrink tube section; (2) enabling a maximum number to be n; (3) scissoring n fibers; (4) enabling the fibers to be exposed from front ends of heat-shrink tubes; (5) preparing a solidifiable resin system; (6) carrying out regulating to enable different fibers to be tested to be consistent in height; (7) enabling resin to become solid; (8) removing the heat-shrink tubes; (9) scissoring fiber sticks to obtain weight m; (10) adding a proper volume of water into a graduated cylinder, and recording a volume V0; (11) completely submerging each fiber stick into the water, and recording a volume V1, so as to obtain the volume V of each fiber stick, i.e., V1-V0; (12) calculating density rho of each fiber stick, i.e., m/V, so as to compare wettability, wherein the higher the density, the lower the internal porosity of the fiber sticks, the better the wettability. The method has the characteristics that the structure is simple, the cost is low, the testing is accurate, test results are direct-viewing, and the applicable range is wide.