Abstract: For the comprehensive utilization of medicinal plant Astragalus complanatus, the chemical constituents of its the non-meidcinal parts and their antibacterial activities were investigated preliminarily. Seven compounds were isolated by using silica gel and LH-20 gel chromatography, and their antibacterial activities against 8 species of bacteria were evaulated. After spectrometric analysis, the obtained compounds were identified as β-sitosterol (1) , β-sitostenone (2) , lawsaritol A (3) , 8-epidioxy-5α,8α-ergosta-6,22E-dien-3β-ol (4) , 3′,7-dihydroxy-2′,4′-dimethoxyisoflavan (5) , D-1-O-methyl inositol (6) and complanatuside (7) . All of the above compounds were isolated from the aerial parts of A. complanatus for the first time. Compound 5 showed inhibition effect on Bacillus cereus, Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Erwinia carotovora, Pseudomonas syringae pv. actinidiae and Ralstonia solanacearum, and the MIC values of compound 5 against three species of plant pathogenic bacteria, including P. syringae, R. solanacearum and E. carotovora, were 37.5, 18.8 and 75 μg/mL, respectively. To our best knowledge, this is the first report about the inhibition effect of 5 on plant pathogenic bacteria.