In this study, the $(1-chi)Ba(Mg_{fraction one-third}Ta_{fraction two-thirds}O_3-chiBa(Co_{fraction one-third}Nb_{fraction two-thirds})O_3$ ceramics($chi$=0.3,0.4,0.5,0.6) were prepared by the conventional mixed oxide method. The ceramics were sintered at the temperature of $1500~1575^{circ}C$ for5 hours in air. The BMT-BCN ceramics have a complex perovskite structure, and have peaks of (101), (102), (201), (202) and (212). Increasing the sintering temperature, dielectric constant was increased. Temperature coefficients of resonant frequency of the specimens were decreasing with increasing BCN content. In the case of the 0.7BMT-0.3BCN ceramics sintered at $1575^{circ}C$ for 5 hours, dielectric constant, quality factor and temperature coefficient of resonant frequency for microwave dielectrics application were a good value of 28, 235500 at ㎓ and -$1.2 ppm/^{circ}C$, respectively.