The effects of Li2CO3-V2O5 (LV) co-doped on the sinterability, phase compositions and microwave dielectric properties of 0.6Mg4Nb2O9-0.4SrTiO3 composite ceramics have been investigated. All specimens were prepared by solid-state reaction method and sintered at 1050-1200oC for 5h. With an amount LV addition, the densification sintering temperature is significantly lowed from 1300oC to 1175oC. The non-stoichiometric compounds Sr(NbTi)O3+δ and Mg4(Nb1-xTix)2O9-δ were confirmed by X-ray diffraction and energy dispersive X-ray analysis. For the specimen with 1.5 wt% LV addition sintered at 1175oC for 5 h exhibited dielectric properties: εr=20.1, Q•f=10 240 GHz, τf =0.15 ppm/oC.