Low temperature ceramics co-fired with copper (LTCC/Cu) was one of the important technologies in ceramic packaging. Due to the low thermal conductivity of LTCC substrates and the low sinter temperature, selecting an appropriate ingredient for LTCC substrates was important. This paper contrasted the influence of several ingredients for LTCC substrates. Protective atmosphere such as nitrogen and hydrogen ambience were used. The thermal conductivity of BSG-AIN system surpasses that of BSG-Al2O3 system in some degree, but sintering temperature of BSG-AIN system is higher than that of BSG-Al2O3 system. The result also shows that the air hole of LTCC substrates could decrease the thermal conductivity, but the introduction of more glass phases and the higher sintering temperature could reduce the number of air holes.