To investigate the reason of spectrum blue-shift in organic multilayer well structure,the organic multilayer well structures,in which the N,N′-Di-［(1-naphthalenyl)-N,N′-diphenyl］-(1,1′-biphenyl)-4,4′-diamine (NPB) and Tris-(8-quinolinolato)aluminum(Alq3) are used as barrier layer and well layer respectively,are fabricated.By changing the number of period and the thickness of well layer,the properties of photoluminescence in organic multilayer well structure are investigated.The blue-shift with the decreasing of well thickness is caused by the overlap of spectrum in the well structure,but not the quantum size effect and exciton confinement effect.