Abstract: As the Covid-19 has brought a huge impact on tourism, scholars in the field are paying more attention to tourists’ emotions and behaviors. And the two aspects have become the key topics. Based on the big data technology, this paper obtains the comment data of tourists who were visiting Yunnan, and analyzes their emotional tendency and characteristics, so as to understand the tourists' perception of the quality of tourism services in Yunnan. Then use visualization technology to display it directly, dig the comment text information in depth, and explore the main factors that affect tourists’ emotional tendency. The results show that: (1) Tourists have different reasons for positive and negative emotional comments. (2) Tourists attach great importance to the experience of the journey. (3) The emotional tendency of tourists towards different cities is closely related to the tourism characteristics of the city. Meanwhile, from the perspective of tourists, this paper attempts to use big data of tourism to study tourists’ preferences. By analyzing the causes of tourists’ positive and negative emotional tendencies, this paper provides ideas for the optimization of tourism service quality in Yunnan Province, and puts forward some suggestions for improvement. In order to improve the quality of tourism service in Yunnan Province and promote the recovery of tourism under the epidemic situation.