In order to improve the drying efficiency and drying quality of fresh apple slices, a low-field nuclear magnetic resonance and imaging analyzer (NMR/MRI) were used to measure the water-migration and thermal-image characteristics of apple slices during microwave hot-airflow drying, microwave vacuum drying and hot-airflow drying respectively. Additionally, the color, texture and microporous structure of the dehydrated apple slices were analyzed. As a result, with the drying process, the signal A2i of the main peak was shifted to the left, and the main state of moisture was gradually changed into immobilized water and bound water. The total signal A2 in the front half of the hot-airflow drying process was decreased rapidly, which indicated that drying was much more difficult in the last stage. The uniformity of temperature in microwave hot-airflow drying was better than that in microwave vacuum drying, which indicated that hot air and fluidized bed had positive effect on improving the uniformity of microwave drying. In the aspect of drying quality, negative pressure environment can avoid the serious oxidative browning of apple slices, but the stability of color difference ΔE needed to be improved during microwave drying. The apple slices had puffing effect during microwave vacuum drying, and the products had the least compressive stress and obvious micro-pore structure. Therefore, microwave vacuum drying was most suitable for developing crisp dehydrated apple slices as leisure food.