Abstract: ABSTRACT OBJECTIVE： To study the compatible stability of doxofylline injection and azlocillin injection. METHODS: The changes in appearance and PH value of the mixture of doxofylline injection and azlocillin injection in 0.9% sodium chloride injection within 6 hours at room temperature were observed and detemined,the contect of which determined by HPLC. RESULTS: Compared with the solution at 0h after mixing，no significant changes were found in appearance and content within 6 hours mixing，however，there was a fluctuation in its PH value. CONCLUSION: the mixture of doxophylline and azlocollin in 0.9% Sodium chloride is stable in quality wthinin 6 hours mixing at room temperature。