The invention discloses a passive natural light omni-directional collection device and method. The collection device comprises a lens array which is distributed in a semi-spherical mode at 180 degrees; light guide optical fibers are disposed at all lens focal points in the lens array correspondingly; all the light guide optical fibers constitute an optical fiber array consistent with and corresponding to the lens array; and the optical fiber array is connected with an illumination device through a main optical fiber. The invention further discloses the collection method. By means of the passive natural light omni-directional collection device, the problem that in existing optical fiber illumination systems, the sun tracking accuracy and condensation transposition optical efficiency are low is solved; and through the passive natural light collection method adopting the collection device, omni-directional natural light can be efficiently guided into a needed scene in real time for providing illumination in daytime, the defect of sun tracking is overcome, the natural light is coupled into the optical fibers to the maximum degree, and operation is simple.