Using a Q-switched Nd: YAG laser the two photon induced fluorescence on borine high sidero-hemoglobin, globulin, tryptophane and tyrosine and their nonlinear effectz have been studied. The two-photon absorption chromophoro in borine high sidero-hemoglobin, borine serumalbumin and globulin are mainly due to the presence of tryptophanc. The obvious difference between fluorescence intensities of tryptophane and tyrosine are caused by their different cross sections. It may be a new approach for selective excitation.