The invention provides a fine mask plate and a manufacturing method thereof. The fine mask plate comprises a mask frame, a first mask made of a metal material and a second mask made of an organic material; the first mask is provided with a plurality of first pixel holes; one or more second pixel holes are formed in the areas, corresponding to all the first pixel holes, of the second mask; as the second pixel holes are formed in the areas corresponding to the first pixel holes, compared with existing FMM, the pixel holes of the smaller size can be provided, and accordingly, OLED devices of the smaller size in the vacuum evaporation process can be manufactured, and the resolution of OLED display products is improved; meanwhile, the hole wall gradient of the second pixel holes can be controlled to be smaller, the second pixel holes are used in the vacuum evaporation process, and thus the incident angle of an evaporation material at the edges of the second pixel holes can be smaller; and accordingly, a coating film shadow area can be decreased, and the resolution of the OLED display products is further improved.