The invention relates to cosmetic powder, oily color paste and a preparation method thereof. The cosmetic powder is subjected to surface treatment by treating liquid; the treating liquid comprises a first modifier and a second modifier; the first modifier is a silane coupling agent with an active group, the general formula is R1(R2)NR3Si(R4)3-a(OR5)a, and in the formula, R1 and R2 are hydrogen, fatty hydrocarbon, or hydrocarbyl containing heteroatoms, R3 is a branched chain or straight-chain alkylene whose carbon atom quantity is 1 to 10, R4 is hydrocarbyl whose carbon atom quantity is 1 to 6,R5 is hydrocarbyl whose carbon atom quantity is 1 to 4, and a is an integer of 1 to 3; the second modifier is an unmodified silane coupling agent, the general formula is R6SiX3, and in the formula, R6 is fatty hydrocarbon whose carbon atom quantity is 1 to 20, and X is halogen, alkoxy whose carbon atom quantity is 1 to 5, or acyloxy whose carbon atom quantity is 1 to 5. The oily color paste comprises the following components in percentage by mass: 30 to 90 percent of cosmetic powder, 5 to 65 percent of grease and 0.1 to 5 percent of a dispersant. The cosmetic powder subjected to surface treatment has high dispersibility and is applied to the oily color paste of the cosmetics; the oily color paste is simple in composition, high in solid content and low in viscosity.