Abstract: Under different characteristics of orange juice and variable conditions of equipment,effects of ultrasound on total number of colonies in orange juice were investigated. The results of orthogonal test showed that the optimum conditions of sterilization are sterilization time 13 minutes,amplitude 70%,pulse on time 30 seconds,pulse off time 25 seconds and orange juice volume 50 ml. The results of analysis of variance showed that the effects of sterilization time,amplitude,pulse time and orange juice volume on sterilization rate are significant(p<0.01) . Compared with heat sterilization,the time of ultrasound sterilizationi ss horter.

Key words: fresh orange juice, ultrasound, heat, sterilization