A key challenge in acid fracturing in fracture-cavity carbonate reservoirs is to create effective fractures in an economically efficient manner，avoiding both excessive displacement rates that inflate costs and insufficient displacement rates that fail to connect the natural vugs. Therefore，it is imperative to determine an optimal critical displacement rate that balances fracture volume against treatment expenditure. Using gelling acid，solid acid，and self-generating acid employed in the Tahe Oilfield，combined with acid fracturing experiments on artificial rock samples under true triaxial conditions，this study innovatively adopted an equal-stepwise displacement method. Based on whether wellbore pressure buildup occurred or the duration of pressure buildup at the bottom hole，the ranges of critical displacement rates for different acid fluid systems and concentrations were determined.Additionally，fracture propagation research was conducted using 10%，15%，and 20% concentrations of gelling acid，solid acid， and self-generating acid. Fracture propagation is influenced by both horizontal stress and cavity attraction. While higher acid fluid concentrations promote rougher fracture surfaces，they reduce the likelihood of activating cavities. The findings are as follows：For 10%，15%，and 20% gelling acid，the laboratory critical displacement rates are 10-11 mL/min，16-18 mL/min，and 18-20 mL/min，corresponding to field displacement rates of 6.3-6.9 m³/min，10.0-11.3 m³/min，and 11.3-12.6 m³/min，respectively. For 10%，15%，and 20% solid acid，the laboratory critical displacement rates are 8-9 mL/min，9-10 mL/min，and 10-12 mL/min，corresponding to field displacement rates of 5.0-5.6 m³/min，5.6-6.3 m³/min，and 6.3-7.5 m³/min，respectively. For 8%，10%，and 12% self-generating acid，the laboratory critical displacement rates are 10-11 mL/min，11-12 mL/min，and 12-13 mL/min，corresponding to field displacement rates of 6.3-6.9 m³/min，6.9-7.5 m³/min，and 7.5-8.2 m³/min，respectively. Concurrently，fracture propagation research is conducted using 10%，15%，and 20% gelling acid at a displacement rate of 45 mL/min，as well as 20% gelling acid at displacement rates of 30，45，and 60 mL/min in the laboratory acid fracturing experiment. The results indicate that within the same acid system，at a constant displacement rate，fractures become more prone to perforation as acid fluid concentration increases，while an increase in displacement rate significantly accelerates fracture propagation.