Based on the working principle of the parallel Vernier effect, a sensitization method to achieve the Vernier effect by superimposing the spectrum is proposed. The Fabry-Perot (F-P) temperature sensing interferometer is used to obtain the measured reflection spectrum. The reflection spectrum of the reference interferometer obtained using the F-P interference principle is superimposed during data processing to achieve the Vernier effect. In the range between 30 ℃ and 55 ℃, the temperature sensitivity of 5.0380 nm/℃ was achieved. Controllable temperature sensitivity can be achieved by changing the cavity length of the reference interferometer. Besides, the dip point of the Vernier envelope for measurement can be placed at any desired wavelength by changing the initial phase of the reference interferometer's incident light. A sensing interferometer with cavity length of 118.60 μm and a reference interferometer with cavity length of 96.60 μm were designed and prepared to conduct a temperature sensitization experiment based on the parallel Vernier effect. The measurement sensitivity of 2.7984 nm/℃ was obtained, which is consistent with the temperature sensitivity achieved by superimposing the F-P reflection spectrum with the same cavity length. The relative error is only 0.57%. Thus, the proposed method is feasible and effective. Besides, it solves the problem that the reference interferometer is vulnerable to the external environment.