The invention discloses a fruit and vegetable composite preservative and a preparation and an application method thereof. The fruit and vegetable composite preservative is prepared from compound solution of rhizoma gastrodiae phenolic extractives and potassium sorbate, wherein the mass ratio of the rhizoma gastrodiae phenolic extractives T1 to the potassium sorbate is 0.005-10. The preparation method for the fruit and vegetable composite preservative comprises the following steps: (1) dissolving the rhizoma gastrodiae phenolic extractives into absolute ethanol to obtain mother liquor A; (2) adding the mother liquor A into pure water, and evenly stirring to obtain rhizoma gastrodiae phenolic extractive aqueous solution; (3) dissolving the potassium sorbate into pure water to obtain potassium sorbet aqueous solution; (4) adding the equal-mass rhizoma gastrodiae phenolic extractive aqueous solution into the potassium sorbet aqueous solution to be evenly mixed to obtain a rhizoma gastrodiae phenolic extractive-potassium sorbate compound solution. The compound solution is sprayed before fruits and vegetables are picked. Compared with the prior art, the fruit and vegetable composite preservative is characterized in that the original quality and storage quality of fruits and vegetables can be improved.