The vibration of the equipment in nuclear power unit will be transmitted to the pipeline connected with it, which is easy to cause pipeline failure, gas leakage and other safety accidents. This paper designed a kind of double dynamic vibration absorber (DDVA) with simple structure and adjustable mass to solve the above problem. Firstly, the parameters of the DDVA were designed according to the actual working condition of pipeline. After continuous iterative optimization based on fixed-point theory and displacement amplitude ratio, the optimal stiffness and damping ratio of DDVA were determined. Furthermore, the vibration absorption effect of the pipeline with DDVA is verified by finite element simulation and compared with the pipeline with single dynamic vibration absorber (SDVA). Finally, the vibration absorption effect of DDVA was verified by bench test. The experimental results show that the DDVA reduces the radial vibration acceleration at the resonant frequency of pipeline by more than 65% (9dB). The research can provide a guiding significance for the vibration absorption design of pipeline.