Fluorescent spectrum was used to study the property of trichrome vitiligo skin. Melanin content and distribution were analyzed and optical model was developed based on the measurement of skin fluorescence and study of skin pathology. Monte Carlo simulation based on this optical model shows good agreement with the experimental result. The study suggests that, trichrome vitiligo skin is an ideal model to study skin melanin content and distribution; fluorescence spectrum can be used to study melanin distribution or other tissue properties in deeper skin (e.g. dermis); the optical model developed and the method to develop it, as well as the spectrum ratio method, can be used in other study of skin optics.