The Chiral SU (3)L × SU (3)R symmetry of QCD breaks down to alower SU (3)v symmetry due to the non-vanishing quark mass-matrix M,accompanied with the origination of Goldstone bosons. The pseudoscalarmeson octet is a good candidate for the eight Goldstone bosons, while theChiral perturbation theory(ChPT) a good candidate for the effective theoryto describe the chiral symmetries of QCD. we count the quark mass-matrixM as O(k2) and expand our effective Lagrangian in order of M, say, ork2. With a construction principle and several construction blocks, we couldobtain our meson Lagrangian order by order。 Construction of the Lagrangian for baryon octet follows a similar way,except for the issue of their not small masses. We adopted the Heavy BaryonChPT(HBChPT), which, in a word, is no more than substituting the orig-inal baryon field operator B(x) with Bv(x)≡ eimv.x B(x), leaving ()μBv asmall quantity. Special technique was made use of to work out the exactform of KN, ηN and πN interaction。 Then we utilized the KN interacting Lagrangian density in the schemeof chiral approach and relativistic mean-field (RMF) theory to figure outthe lst order self-energy correction of kaon in nuclear matter. We discov-ered effective mass and optical potential of K+ are identical with that ofK- respectively. Effective mass of kaon in nuclear matter will decreasewith the increasing of nuclear density, but has nothing to do with the KNSigma term. Optical potential of kaon in nuclear matter is positive andwill increase as the nuclear density increases. In conclusion, as long as thegiven K N interacting Lagrangian is right, its impossible that there existskaons bound state in nucleus. But probably kaon may react with nucleonsin nucleus to produce h-hyperons nucleus。 Finally, effective mass and optical potential of η in nuclear matter werecalculated with the help of the η N interacting Lagrangian obtained fromthe ChPT in the scheme of RMF. Negative optical potential with not smallabsolute values conveys to us information about the bound depth of η innuclear matter while smaller effective mass than in vacuum tells us aboutthe width of the potential well. With the increasing of nuclear density, bothdepth and width increase, providing possibilities for existence of boundstates of η in nuclear matter。