The invention provides a delayed gelatinizing composite plugging liquid and a preparation method thereof, and the method comprises the following steps: adding 0-1.0% of a
delay agent into 100% of
fresh water according to the total percentage of
fresh water, continuously adding 1-10% of a
polymer suspending agent A and 0.5-3% of a
polymer suspending agent B after the
delay agent is dissolved, continuously adding 0.1-3% of a cross-linking agent after the
polymer suspending agent is dissolved, and uniformly stirring to obtain the delayed gelatinizing composite plugging liquid. And then sequentially adding 50-100% of a curing main agent, 5-20% of a curing auxiliary agent, 0-100% of a density
regulator, 0-2% of an activating agent and 0-3% of a
retarder, and stirring for 20-60 minutes at the speed of 800r / min until
solid-phase particles are uniformly dispersed, thereby obtaining the water-dispersion-resistant delayed gelatinizing composite plugging liquid suitable for the high-temperature fractured formation. The plugging
working fluid disclosed by the invention is good in pumpability, controllable in crosslinking time and
curing time, capable of resisting the temperature of 150 DEG C or above, simple in construction process and applicable to plugging operation in the high-temperature deep stratum drilling process.