There are problems such as excessive diffusion range and waste of materials when traditional fluidized soil is used in bored cast-in-place pile projects in karst areas. It is proposed to solve this problem by adding admixtures to shorten the initial setting time. Considering different admixtures, such as early strength agents, rapid setting agents and water reducing agents, the improvement effect of various admixtures on the initial setting time of fluidized soil is studied through laboratory tests first. Then, the appropriate admixture is preliminarily determined, and its influence on the fluidity and strength of fluidized soil is studied. Finally, the fluidized soil mix ratio suitable for bored cast-in-place pile treatment in karst areas is proposed. The results show that: The addition of sodium sulfate and water reducing agents can significantly shorten the initial setting time of fluidized soil, with water reducing agents having a better effect, while other early strength and rapid setting agents have significantly lower coagulation-promoting effects than sodium sulfate and water reducing agents. Although sodium sulfate can promote coagulation, the strength of the fluidized soil mixed with sodium sulfate will be slightly lower than that of the fluidized soil without sodium sulfate when the age reaches 14 and 28 days. For the fluidity and strength of fluidized soil, the addition of a water reducer is beneficial, while the addition of sodium sulfate has certain negative effects, but the impact is relatively small. Taking into account both performance and cost factors, it is recommended that the fluidized soil used in bored pile projects in karst areas should be a mixture of 10% cement, 6% water reducer, and 3% sodium sulfate.