Research on modeling and analyzing adaptive business processes based on Web services is very important for developing and deploying applications in the mobile Internet. In order to modeling and verifying the reliability and adaptability of services effectively, in this paper, a probabilistic approach is proposed to formally describe and analyze the reliability properties of adaptive business processes. First, based on the semantic similarity of services and compatibility of data types, which provide candidate set for the adaptable application, and business processes can be adaptive according to the change of circumstance. Then, the probabilistic model checking is used to analyse the soundness and reliability of adaptive business processes. Finally, an video transfer application is modeled and verified based on the proposed method, which shows that the approach provides an effective underlying guideline for modeling and analyzing adaptive applications in the mobile Internet.