Abstract: Objective To introduce the method of avuncular index（AI） calculation. Methods Identity by decent coefficient, coancestry coefficient and AI law were employed in identification of uncle-niece relationship, when autosomal STR loci were detected to determine controversial uncle-niece relationship. Results The results of AI calculation were coincidental using identity by descent coefficien, coancestry coefficient and AI law. Conclusion The results are coincidental using three methods in the different situations. AI index is higher with participation of children’s mother.

Key words: forensic genetics, kinship, avuncular index