Abstract: To preserve fibrinolytic activity of bromelain in pineapple juice, the effect of different pressures, temperatures and pressure holding times on the fibrinolytic activity of bromelain was investigated. Stability of bromelain in simulated gastrointestinal digestive fluid were also studied. Results showed that all the factors had significant effects on fibrinolytic activity of bromelain.At 300MPa ( 30℃, 10min) , the fibrinolytic activity of bromelain was 65.54% higher than that of fresh pineapple juice.After 4h incubation in simulated gastric fluid or intestinal fluid at 300MPa ( 10 min, 30℃) , the residual fibrinolytic activity of bromelain in pineapple juice was 37.91% or 85.33%, respectively, which were both higher than that of fresh pineapple juice. It indicated that ultra high pressure treatment could improve the fibrinolytic activity of bromelain in pineapple juice and its tolerance to simulated gastrointestinal fluid by adjusting the processing parameters.