The invention provides a method and device for detecting fracture-type reservoir fluid based on weakness parameters, and relates to the technical field of petroleum exploration. The method comprises the steps that three-dimensional seismic data of a fracture-type reservoir is obtained, and the three-dimensional seismic data is processed into azimuthal incidence angle gathers; according to the incidence angle gathers, an inversion algorithm where amplitude changes along with azimuthal angles is adopted for calculating aeolotropy parameters; according to the aeolotropy parameters, the tangentialweakness parameter and the normal weakness parameter of the fracture-type reservoir are calculated, and a ratio of the tangential weakness parameter to the normal weakness parameter is determined asan original fluid factor; according to a lame constant of a fracture-type reservoir background medium, the original fluid factor is corrected to obtain a secondary fluid factor; according to a fracture aspect ratio of the fracture-type reservoir, the secondary fluid factor is corrected to obtain a fluid factor result; the fluid factor result and a threshold value interval set in advance are compared to determine a reservoir fluid type corresponding to the fluid factor result.