Acid Yellow 42 is an acid dye, bright yellow powder. Soluble in water, the aqueous solution is lemon yellow. The aqueous solution was added with concentrated hydrochloric acid and concentrated sodium hydroxide, and there was no change in color. Soluble in ethanol, it is lemon yellow, slightly soluble in acetone. The invention can be used to prepare a composite dye for nylon sea island microfiber leather fabrics and a three-in-one crayon which is easy to process, easy to scrub with water, relatively environmentally friendly, and integrates crayons, color powder and gouache.