The invention provides a workover fluid and its preparation method and application. The mass percent composition of the workover fluid is: fluff agent 0.4%-0.8%, layering agent 1.0%-2.0%, nucleating agent 0.1%-0.3% %, film forming agent 0.2%~0.5%, oxygen scavenger 0.5%~1.0%, fungicide 0.1%~0.2%, potassium chloride 3.0%~5.0%, high temperature stabilizer 0.5%~1.0%, hydrogen sulfide removal agent 0.5% to 1.0%, corrosion inhibitor 0.1% to 0.2%, waterproof locking agent 0.5% to 1.0%, drainage aid 0.5% to 1.0%, and water 86% to 93%. The workover fluid provided by the invention has high Stability, good sand-carrying performance, strong drainage ability and little damage to the formation, can effectively temporarily plug the formation, and solve the problem of low-pressure and low-permeability reservoir leakage well workover in the prior art by reducing the workover fluid density There are still technical problems of leakage phenomenon.