Abstract: In order to develop the new doxycycline prepration,the best formula of doxycycline injection was selected by orthogonal experiments on the basis of single factor experiment and determined by high perfomance liquid chromatography with ultraviolet detector. The injection’s appearance, clarity, pH value and so on all meet the requirement of Veterinary Pharmacopoeia of the People’s Republic of China. The calibration curve was linear in the concentration range of 5 to 100 μg/mL, R²＝0.9992, with the average recovery rate of 99.87%,the intra-day CV≤0.42%, the extra-day CV≤0.96%. The concentration of doxycycline injection is 98.3%. The results show that the determination method is steady reliable, the final formula is reasonable and the content meets the requirement.

Key words: Doxycycline injection; orthogonal experiment; determination