The invention discloses dewatering liquid of curing water for workover fluid and a dewatering method thereof. The used dewatering liquid is prepared from 5 percent of potassium chloride, 15 percent of calcium chloride and 80 percent of fresh water in percentage by mass. A pump truck and a ground pipeline are connected; pressure test is performed on the pipeline, a wellhead and a production tree; the pressure test pressure is smaller than the minimum pressure bearing pressure of the pipeline, the wellhead and the production tree; the curing water workover fluid in a pit shaft is replaced by fresh water; the dewatering liquid is replaced into an oil pipe; a casing pipe gate is closed; the dewatering liquid is positively extruded into the reservoir from the oil pipe according to the quantity of 1t for per meter of oil layer; the replacing clean water of the volume of the oil pipe is extruded in from the oil pipe; and after the shut-in reaction for 2h, the dewatering construction of the curing water for the workover fluid can be completed. The dewatering problem of the curing water after the well control of the curing water workover fluid is solved; the seepage rate of the reservoir is effectively protected; and the technical support is provided for safe pit operation proceeding of a leaking oil gas water well.