The effect of sintering temperature on resistance temperature coefficient and microstructure of ZnO-based linear resistors was studied using the conventional ZnO+MgO+Al₂O₃+SiO₂ system. It is found that the resistance increases from milliohm level to ohm level as the sintering temperature decreases, while the resistance temperature coefficient is completely negative when the sintering temperature is at 1340 ℃. The resistance temperature coefficient turns from negative to positive when the sintering temperature is at 1320 ℃ and then completely turns to positive when the sintering temperature decreases to 1280 ℃.