The　influence　of　annealing　time　and　secondary-rolling　reduction　ratio　on　grain　boundary　character　distribution　(GBCD)　in　an　FCC　CoCrFeMnNi　high-entropy　alloy　were　investigated　via　electron　backscatter　diffraction　(EBSD).　The　results　show　that　the　processing　of　10%　cold-rolling　reduction　subsequently　with　annealing　at　1073　K　for　10　h　induces　a　high　frequency　of　low　coincident　site　lattice　(CSL)　boundary　with　＞　70%,　thereby　effectively　achieving　GBCD　optimization.　As　annealing　time　increases,　low-Sigma　CSL　(Sigma　＜=　29)　boundary　frequency　first　decreases　and　then　remains　constant　at　approximately　60%.　The　secondary-rolling　reduction　ratio　followed　by　annealing　at　1073　K　for　10　h　also　exerts　a　substantial　influence　on　GBCD.　As　the　reduction　ratio　increases　from　6%　to　40%,　the　low-Sigma　CSL　(Sigma　＜=　29)　boundary　frequency　first　increases　and　then　decreases.