Carrots contains high level of provitamin A carotenoids, especially β-carotene, which plays the function of antioxidation and scavenging free radicals in vivo. But they also have high level moisture content. This character negatively impacts the length of time that carrots can be stored. Dehydration of carrots can effectively increase storage time and retain nutrition. But in the drying process of carrots, the β-carotene degradation reaction rate would be significantly increased by destruction of tissue integrity, temperature rise, and contacting with light and oxygen, which could change the nutritional value of carrots. Carrots were dried by oxygen limited heat pump firstly, and then in vitro digestion model was used to evaluate the effect of different drying medium and oil on bioaccessibility of β-carotene in carrots during drying process. The bioaccessibility of β-carotene was measured by β-carotene release rate in supernatant by using low-speed centrifugation and β-carotene micellar rate in micelle phase by ultrafiltration. Although there was negative impact on β-carotene retention rate by drying process, there was positive impact on the bioaccessibility. Especially when CO2 was used as a drying medium, it increased the retention rate and bioaccessibility of β-carotene significantly. In addition, there was significant increase in the release rate and micellar rate of β-carotene in fresh and dried carrots when oil was added. Anyhow, there was significant increase of bioaccessibility of carrots by heat pump drying and adding oil. This may enhance the bioavailability of human beings.