The invention provides a dense optical fiber array spectral beam combining device and method. By adoption of a beam concentrating collimation optical system for realizing dense optical fiber arrays, an optical path of the beam combining device can be shortened, compact spectral beam combining is realized, and fast and slow axis collimation of laser can be realized as well. The beam concentrating collimation optical system consists of a first optical component and a second optical component, the first optical component is a slow axis collimation lens, and the second optical component is a fastaxis collimation lens.