The rare-earth-transition-metal ternary alloy of TbMn6Sn6 was fabricated by conventional arc-melting method. The alloy was examined by X-ray diffraction and the refinement showed its HfFe6Ge6-type crystal structure. The magnetic structures were investigated by combining the 119Sn and 57Fe Mssbauer spectra at different tempera-tures from 20 K to 390 K
and a 90o spin transition behavior was observed at about 310 K.