Abstract: A nuclide ²³⁹Pa was produced via a multinucleon transfer reaction by 60 MeV/u ¹⁸O ions bombardment of natural uranium. Protactinium was radiochemically separated from the irradiated targets. ²³⁹Pa has been identified by using observation and analysis of γ-rays of ²³⁹Pa and ²³⁹U as a daughter nucleus of ²³⁹Pa. The half-life of ²³⁹Pa was determined to be （106±30） min. Long lived isotopes like ²³²Th and ²³⁸U give a possibility of determining the duration of nucleosynthesis whereas intermediate lived nuclei like ²³⁵U can give information about the time history of the production function. Generally the universe age is deduced through the ratios of the ²³²Th/²³⁸U, ²³⁵U/²³⁸U or ²⁴⁴Pu/²³⁸U with formular N_A(Δ)/N_B(Δ)=(P_A/P_B)f(λ_A，λ_B，S₀，λ_R，Δ). The influence of the novel long half-life of ²³⁹Pa on the universe age estimate is simply mentioned by ²³⁹Pa decay path.