Common wheat bread, common oat bread (20% (w/w) oat flour substitution), oat sourdough bread (10% oat flour substitution＋10% oat sourdough substitution) and freeze-dried oat sourdough bread (10% oat flour substitution＋10% freeze-dried oat sourdough substitution) were analyzed for their volatile compound composition by solid phase micro-extraction/gas chromatography-mass spectrometry (SPME/GC-MS) in order to explore the effects of oat sourdough starter and freeze drying of sourdough on volatile flavor compounds of bread. The oat sourdough was fermented with starter culture of Lactobacillus plantarum. A total of 57 compounds were identified in the four breads, including alcohols, acids, aldehydes, esters, ketones, aliphatic compounds, aromatic and heterocyclic compounds. The most abundant volatile compound category in all samples was alcohols, followed by aromatic and heterocyclic compounds, aldehydes and acids. Breads supplemented with oat flour showed more kinds of volatile compounds. Toluene, heptanol, trimethylene acetate, caprylic acid were determined in oat breads but not in wheat bread. Some flavor compounds or flavor precursors were lost during freeze drying. Diacetyl, 2-pentanone, ethyl heptanoate, 2-acetylthiazole and geranylacetone were unique in oat sourdough bread.