The FH2- anion has a stable structure that resembles a configuration in the vicinity of the transition state for neutral reaction F + H-2 -> HF + H. Electron photo detachment spectra of the FH2- anion reveal the neutral reaction dynamics in the critical transition-state region. Accurate quantum dynamics simulations of the photodetachment spectra using highly accurate new ab initio potential energy surfaces for both anionic and neutral FH2 are performed and compared with all available experimental results. The results provide reliable interpretations for the experimental observations of FH2- photoelectron detachment and reveal a detailed picture of the molecular dynamics around the transition state of the F + H-2 reaction. The latest high-resolution photoelectron detachment spectra [Kim et al. Science, 2015, 349, 510-513] confirm the high accuracy of our new potential energy surface for describing the resonance-enhanced reactivity of the neutral F + H-2 reaction.