Binary2Source function similarity detection is regarded as one of the fundamental tasks in software composition analysis. In the existing binary2Source matching works, the 1-to-1 matching mechanism is mainly adopted, where one binary function is matched against one source function. However, it is found that such a mapping may be 1-to-n (one binary function is mapped to multiple source functions) due to the existence of function inlining. A 30% performance loss is suffered by the existing binary2Source matching methods under function inlining due to this difference. Aimed at the matching requirement of binary to source functions in the scene of function inlining, a binary2Source function similarity detection method for 1-to-n matching is proposed in this study, which is designed to generate source function sets as the matching objects for the inlined binary functions to make up for the lack of the source function library. The effectiveness of the proposed method is evaluated through a series of experiments. The experimental data indicate that the method can not only improve the existing binary2Source function similarity detection ability but also identify the inlined source code functions, helping the existing tools better cope with the challenges of inlining.