HD 140283, a nearby extremely metal-poor subgiant star, formed shortly after the big bang, is thought to be the oldest star to date, and also a typical weak r-process star. Study of this star is of great significance for understanding the early history of the universe, and enriching the element nucleosynthesis theory. Based on the observed abundances of weak r-process star HD 140283 and theoretical yields of single supernova (SN), we fit the observational elemental abundances (from O to Zn) to the entire library of single SN yield, and derive that HD 140283 may have been born from a nebula polluted by the explosion of supernova whose progenitor mass is 22.5 M⊙(the subscript \⊙" means the solar mass). Based on the same method, we study the other ve typical weak r-process stars, and respectively derive the progenitor masses of supernova which have polluted the nebulas forming these stars. Furthermore, the possible astrophysics sources of weak r-process are inferred.