The main purpose of the work was to find out the relationship between browning reactions and color changes of apple slices during the hot air-explosion puffing drying (HA-EPD).The results showed the HA pre-drying of hot air (HA) had an important effect on final apple slices color.The moisture content (wet basis,w.b.) and water activity (aw) of apple slices dried by HA-EPD were less than 50g/kg and 0.106,respectively.The free water was almost evaporated at the end of pre-drying process and about 77.78% of bound water was removed after HA-EPD.The color index had a significant correlation (p<0.05) with moisture content (w.b.) and water state during HA-EPD.The reduced ascorbic acid,dehydroascorbic acid (DHAA) and total ascorbic were declined to 1.59 × 10-2 g/kg,0.60 × 10-2 g/kg and 2.48 × 10-2 g/kg,respectively.Moreover,there were significant correlations (p<0.05) among reduced ascorbic acid,DHAA and total ascorbic acid during HA-EPD.Total phenols were decreased to 25.64× 10-3 g/kg and had a significant correlation (p<0.05) with color index during HA-EPD.The fructose and glucose were reduced with the abrupt increase of 5-hydroxymethyfurfural (5-HMF) during EPD.The major browning reaction of apples slices during the pre-drying process was enzymatic browning,while non-enzymatic browning played a crucial role during EPD process.