The invention provides a rose petal extracting method and a drying device thereof, belongs to the field of plant extraction, and solves the problem that in the prior art, the extraction quality is nothigh. The plant petal extracting method comprises the following steps: A, preparing: selecting screened clean plant petals, and placing a squeezing device and a drying device in a container; B, squeezing: sending the plant petals for use into the squeezing device, and squeezing the plant petals in a pressure pressing manner under the action of the squeezing device to obtain liquid flower juice and a solid substance to be extracted; C, separating and storing: storing the flower juice in a sealed container, and adding a preservative into the flower juice; D, drying. The plant petal extracting method is high in extracting quality.