Two new chromophores with carbazole as molecular focal point bearing either one o-pyridine-benzothiadiazole unit or two o-pyridine-benzothiadiazole units at the periphery respectively, named as 2,8-(o-pyridine-benzothiadiazole)-N-ethyl-carbazole (CPTZ1) and 2,8-bis(o-pyridine-benzothiadiazole)-N-ethyl-carbazole (CPTZ2), were synthesized and characterized by IR spectra, 1H NMR spectra and MS. The influence of proton upon one-photon and two-photon fluorescence about these two compounds was discussed. Stern-Volmer equation gives that the S-V constants (k1PSV) of one-photon fluorescence (1PF) of CPTZ1 and CPTZ2 are 0.04 and 0.10 L·mol-1, respectively; while the k2PSV of two-photon fluorescence (2PF) of CPTZ1 and CPTZ2 are 0.20 and 0.22 L·mol-1, respectively. Obviously, two-photon (2P) fluorescence detection presented more sensitivity than one-photon (1P) fluorescence response, which exhibits the potential application of two-photon sensor in PH detection.