The present invention relates to the technical field of synthesis and application of compounds used in the metal corrosion, and specifically discloses a novel rosinyl imidazoline compound and a synthesis method and application thereof. A starting raw material of the rosinyl imidazoline compound is rosin acid, the raw material is single, and a synthesis route and operation are simple. The method for preparation of an inhibitor from the synthesized compound is simple, and the inhibitor can be prepared only by dissolving the compound in dimethyl formamide, after the compound is dissolved in the dimethyl formamide completely, dissolving in water, and evenly mixing. This inhibitor is safe and environmentally-friendly, has excellent corrosion inhibition effect, and can be used for oil and gas field ground gathering and transportation pipelines to prevent corrosive gas corrosion damage to steel gas and other metal materials, and reduce the corrosion losses.