The present invention discloses a low-cost direct current power carrier communication bus circuit. The circuit includes a first line, a second line and a third line. The first line is connected with a resistor R7 and an operational amplifier U2. The input end of the resistor R7 is connected with a voltage access point. A collector of a transistor Q1 is connected with the first line. An emitter of the transistor Q1 is connected with a resistor R10. The emitter of the transistor Q1 is connected with a voltage grounded point. The third line is connected with a resistor Q4. A non-inverting input end of an operational amplifier U1 is connected with the first line. The output end of a resistor R3 is connected with the voltage grounded point. The circuit can be applied to large power load, and realizes carrier bus communication. The third line cooperates with the other two lines to complete communication. Compared with all existing site buses, the circuit has the absolute advantage in material cost, and saves the construction cost.