To study the effect of different amino-containing precursors to meat flavor formation， peptides fractions in molecular weights of <1 ku， 1-5 ku， and >5 ku， were separated from enzymatically hydrolyzed chicken by ultrafiltration， and the samples of free amino acids were prepared by hydrochloric acid hydrolysis of the enzymatically hydrolyzed chicken. A total of eight model thermal reactions subdivided into two types， i.e.， with or without the addition of oxidized chicken fat， were carried out using the samples of peptide fractions and the free amino acids， and glucose as reactants. For the reaction products， the absorbance at 420 nm and pH values were measured， and the volatile flavor compounds were analyzed by solid phase microextraction （SPME） and gas chromatography-mass spectrometry （GC-MS）. It showed that for both the two types of reactions， with the increase of molecular weight of the amino-containing samples， absorbance values at 420 nm and total amounts of volatile compounds were decreased. These might be due to the amino-containing precursors of larger molecular weights from the enzymatically hydrolyzed chicken possessing a lower reactivity. Among them， the free amino acid samples behaved the best in generation of sulfur-containing compounds， and the <1ku or 1-5 ku peptides samples behaved the best in generation of pyrazine compounds. On the other hand， because of affect of lipid degradation products especially carbonyls in the oxidized chicken fat on the Maillard reaction， when the oxidized chicken fat was added， absorbance values at 420 nm of the reaction solutions were slightly increased， whereas total amounts of volatile flavor compounds were considerably decreased. Meanwhile， amounts of some alkane chain compounds （e.g. 2-methyl-5-propylthiophene） were increased and a new alkane chain compound 2-butylpyridine emerged with the addition of the oxidized chicken fat.