Preparation method of imidazoline inhibitor for drilling fluid

The invention discloses a preparation method of an imidazoline inhibitor for drilling fluid. The method is characterized by comprising the following steps: a, feeding a substance A and a substance B based on the molar ratio of 1-2: 1, and synthesizing a first intermediate; b, adding water to the first intermediate synthesized in step a based on the molar ratio of water to the substance A of 1.1-2:1 under the temperature of 50-100 DEG C; c, adding a substance D to a hydrolysate produced in step b so as to obtain a second intermediate body; d, adding a substance E to the second intermediate obtain in step c so as to obtain a third intermediate; e, adding water solutions of alkali, water and the substance A to the third intermediate obtained in step d so as to obtain a dark brown reacting product; and f, mixing the dark brown reacting product and a substance F to obtain the dark brown liquid which is the final product. The imidazoline inhibitor prepared through the method has the characteristics of being obvious