Objective: To achieve the simultaneous utilization of glucose-xylose in the fermentative production of L-lactic acid by Escherichia coli. Methods: E.coli JH16 (E.coli B，△frdBC△pflB△ackA△adhE，ldhA::ldhL)， an engineered L-lactic acid productive stain was chosen as start strain， and the xylose transport and metabolism relevant genes xylFGH， xylE， xylA were knocked out by Red homologous recombination to get an xylose utilization deficient strain， E.coli JH16031. The glucose transport and metabolism relevant genes crr， malX， galP were also knocked out from E.coli JH2705(E.coli JH16， △ptsG△mglB) to get a glucose utilization deficient strain， E.coli JH27071. The two resulting strains were co-cultured to form an E.coli synthetic microbial community. Shake flasks and 5 L fermenter experiments were carried out to optimize the inoculum ratio of the two strains of this synthetic microbial community for mixed sugar fermentation. Results: When using 60 g/L glucose and 40 g/L xylose for fermentation， with an initial inoculum ratio of 1∶50 between JH16031 and JH27071， initial OD600nm=0.5， the community has the the highest efficiency for sugar utilization， consuming 97% of total sugars in 84 h and ending the fermentation in 96 h. The L-lactic acid yield reaches 92 g/L， and sugar-acid conversion rate is 91%， with glucose consumption rate as 705 mg/(L·h)， xylose consumption rate as 435 mg/(L·h)， L-lactic acid productivity as 951 mg/(L·h). Conclusion: The constructed E.coli synthetic microbial community enables the simultaneous utilization of glucose and xylose for L-lactic acid fermentative production with mixed sugars as carbon sources， which may benefits the usage of low-cost lignocellulose in industrial fermentative process with improved sugar utilization efficiency.