Bending　characteristics　of　four-core　optical　fiber　Bragg　gratings(MCFBGs)　according　to　bending　curvature　and　bending　direction　is　analyzed　using　coupled-mode　theory　and　mechanics　of　materials　in　this　paper.　The　simulated　results　show　that,　bending　makes　the　resonant　wavelength　of　the　four-core　MCFBGs　shift,　two　FBGs　that　in　the　catercorner　of　square　matrix　cores　have　the　same　wavelength　changes(Delta　lambda(1)　=　Delta　lambda(3),　and　Delta　lambda(2)　=　Delta　lambda(4)),　but　have　the　opposition　direction　of　shift.　The　wavelength　difference　of　two　FBGs　at　the　catercorner　of　the　square　matrix　(Delta　lambda(13)　or　Delta　lambda(24))　is　proportional　to　the　bending　curvature.　The　bending　sensitivity　of　the　wavelength　difference　(d(Delta　lambda(13))/d　rho　or　d(Delta　lambda(24))/d　rho)　is　changed　with　a　different　bend-directions.　The　orientation　of　the　bending　was　determined　by　the　arctangent　of　the　ratio　of　the　wavelength　difference　Delta　lambda(13)/Delta　lambda(21).　The　sensitivity　of　the　wavelength　difference　between　cores　is　twice　to　the　sensitivity　of　the　reflection　Bragg　wavelength　changes.