Abstract: Four PGPR(Strain No.: A-Hsg， B-ls13， C-lhs11， D-lhs14) strains isolated and screened from the red clover (Trifolium pratense) and the white clover (Trifolium repens) in rhizosphere in Lanzhou were used to produce single or compound inoculum. A pot experiment was carried out to determine effects of the inoculum on growth character and quality of red clover. The results indicate that the produced inoculants are accorded with the quality criterion of agricultural microbial fertilizer ofChina(GB 20287-2006). The compound inoculant treatment, AD, has a significant effect on plant height and root length which are enhanced 3362% and 4620% respectively compared to the control (P0.05). The compound inoculant treatments, AB and AD, could improve the aboveground biomass by 101.69% and 94.98% respectively comparing to the control (P0.05), while the compound inoculant treatment, BC and AD, could increase underground biomass by 197.63% and 151.18% (P0.05) respectively. The phosphorous contents of the plants treated by the compound inoculants (AC, AD and BCD) are increased compared to control. Moreover, the compound inoculants (ABCD) enhances nitrogen content significantly (14.77%) compared to the control (P0.05). Three treatments, ABD, BCD and ABCD, could improve the crude protein contents, and the crude protein content of the treatment of ABCD is improved by 14.26% compared to the control (P0.05). Thus, the compound inoculants (AD, AB, BC, AC, ABD, BCD and ABCD) show good promoting effects on the growth and the quality of the red clover, and can be used as compound biofertilizer for the further study.