The invention discloses a DTS-based filling pile completeness detection and optical fiber heating influence radius determination method. At first, the dimension of a model test pile is determined according to engineering pile dimension and a distance resolution ratio of a DTS collector; a model box and a steel bar cage are manufactured according to the determined dimension; optical fiber is arranged along a center axial line along the length direction of the model box; the optical fiber is arranged in a mode of sequentially forming loops parallel to the center axial line; the adjacent opticalfiber with a certain length is reserved at the outer side of the model box; whether a breaking point exists in a optical fiber line or not is detected; concrete is poured in the model box; after maintenance curing, a temperature test is started; a path of optical fiber with the parallel loops is selected; optical fiber heating devices are connected onto two ends, exposed out of the model box, of the selected optical fiber; the temperature distribution on each section of the optical fiber at different heating power is measured; an influence radius of the heating optical fiber at the corresponding heating power can be determined according to setting space between every two sections of optical fiber. The invention provides the standardized theoretical basis for detecting the filling pile completeness by using the DTS; the application range for detecting the filling pile completeness by using the DTS is expanded.