The detecting method of measuring axial force of double-walled model pipe pile by fiber Bragg grating (FBG) is proposed. The relationship between the strain change of the model pipe pile and the stability and drift of the central wavelength of the fiber grating is discussed. FBG sensor is packaged in the external tube of the mode pipe pile, and is attached on the internal tube of the mode pipe pile. The strain gauges are stuck on the same position of fiber grating of external tube and internal tube of mode pipe pile, respectively. After the vertical stress is exerted on the model pipe pile, the strain of the model pipe pile is tested, and the test results of the FBG sensor and the strain gauge are compared with the theoretical formula. It is found that there are errors between them, but within test requirements. When the vertical load of 5 kN is applied to the external tube, the maximum strain measured by the FBG is 59.2 με and the relative error is 4.9%. The maximum strain of internal tube measured by the FBG is 122.3 με with a relative load of 5 kN, and the relative error is 7.2%. These errors are allowed for the engineering test requirements.