The microwave dielectric properties and microstructure of the (1-x)$Mg_4Ta_2O_{9-x}TiO_2$(X=0, 0.3, 0.4) ceramic were, investigated. The specimens were prepared by the conventional mixed oxide method with sintering temperature of $1350^{circ}C$∼$1425^{circ}C$. According to the XRD patterns, the (1-x)$Mg_4Ta_2O_{9-x}TiO_2$(X=0, 0.3, 0.4) ceramics have the $Mg_4Ta_2O_{9}$ phase(hexagonal). The dielectric constant($varepsilon$$_{gamma}$) and density increased with sintering temperature and mole fraction of x. To improve the quality factor and the temperature coefficient of resonant frequency, TiO$_2$($varepsilon_{r}$=100, $Q{ imes}f_{r}$=40,000GHz, $ au$$_{f}$=＋450 ppm/$^{circ}C$) was added in $Mg_4Ta_2O_{9}$ ceramics. In the case of the $0.7Mg_4Ta_2O_{9}$-$0.3TiO_2$ and the $0.6Mg_4Ta_2O_{9}$-$0.4TiO_2$ceramics sintered at $1400^{circ}C$ for 5hr., the microwave dielectric properties were $varepsilon$$_{gamma}$=11.72, $Q{ imes}f_{r}$=126,419GHz, $ au_{f}$=-31.82 ppm/$^{circ}C$ and $varepsilon_{r}$=12.19, $Q{ imes}f_{r}$=109,411GHZ, $ au$$_{f}$= -17.21 ppm/$^{circ}C$, respectively.