According to the relationship between dosage and effect, the time course of analgesic was determined after oral administration of Xiaohuoluo Pills to mice. Based on this experiment, contrasting the commercial pills with the reference preparation, the bioavailability of Xiaohuoluo Pills was studied. It was shown that the bioavailability of different batches of product from the same factory was different. This method was good for the study of compound preparations of Chinese materia medica.