Enthalpies of solution of glycine and its oligomers in aqueous solutions of trimethylamine N-oxide (TMAO) or urea have been measured by calorimetry at 298.15 K. The results obtained were used to calculate the heterogeneous enthalpic interaction coefficients between glycine and its oligomers and the molecule of TMAO or urea in water and the transfer enthalpies (ΔtrHm) of the glycine and its oligomers from water to aqueous solutions of TMAO or urea. The results are discussed in terms of solute-solute and solute-solvent interactions. The influence of trimethylamine N-oxide (TMAO) and urea on the structure of water has been investigated by molecular dynamics simulation. The results show that water affected by TMAO forms stronger H-bonds and is more ordered than pure water. The results obtained by molecular dynamics simulation support transfer enthalpic changing trend of glycine and its oligomers in aqueous solutions of trimethylamine N-oxide (TMAO) or urea.