@i_mazlov I get it, thanks for your reply.

Hi everyone!
After using MergeDocument to import a file, I need to manually specify the texture paths in the Project Asset Inspector. Am I importing the files incorrectly, or is there an additional setting I need to configure?

import c4d

def main() -> None:
    doc = c4d.documents.GetActiveDocument()
    target_flie = r"D:\01\test.c4d"
    c4d.documents.MergeDocument(doc, target_flie, c4d.SCENEFILTER_OBJECTS | 
                                           c4d.SCENEFILTER_MATERIALS | 
                                           c4d.SCENEFILTER_MERGESCENE)
if __name__ == '__main__':
    main()