An organoselenium-catalyzed oxidative exo-selective ring-closing reaction of unsaturated alcohol promoted by 1-fluoropyridinium triflate (FP-OTf), N-fluorobenzenesulfonimide (NFSI) and Selectfluor has been theoretically studied. The reaction mechanisms were proposed after detailed computational screening, the corresponding potential Gibbs energy surfaces were drawn, and catalytic cycles were proposed. The conjugation effect in ring-closing transition state structure determined the reaction exo-/endo- selectivity, and the intramolecular steric repulsion in β-elimination transition state structure determined the reaction (E)-/(Z)- selectivity. The influence of oxidant species and addition of NaF on the reaction yield was discussed in detail.