This paper study author simultaneously engaged in multiple affiliations based on bibliometric data covered in the Web of Science for the 2017-2021 period. Based on the affiliation information in publication records, we propose a general classification for multiple affiliations within-country or cross-country for analyzing authors' behavior in multiple affiliations and preferences of host countries across research fields. We find a decrease in publications led by international multi-affiliated authorship after 2020, and China has shown a falling trend after 2018. More G7 countries are active in fields like Social Sciences, Clinical and Life Sciences. China, India, and Russia are active in physical sciences-related fields. Countries prefer to affiliate with G7 countries, especially in Clinical and Life Sciences. These findings may provide more insights into the understanding of the behavior and productivity of multi-affiliated researchers in the current academic landscape.