Yellow Monascus pigments were prepared after extractive fermentation in nonionic surfactant micelle aqueous solution, in
which transferring of Monascus pigments from nonionic surfactant aqueous solution to IL by novel IL based Winsor I microemulsion extraction and removal of orange Monascus pigments via aminophilic reaction were applied. Yellow Monascus pigments exhibited no aminophilic reaction by replacement of 4-H-pyran cycle in the orange Monascus pigments with 2-H-pyran cycle. This fundamental evidence sheds light on the relationship between structure and cytotoxicity of Monascus pigments.