Abstract: A circuit for controlling power supply startup includes a switch-controlling module and a switch module; a signal-detecting terminal is electrically connected to a negative electrode of a battery lead clamp and a negative electrode of a startup power supply respectively; a signal-detecting terminal and a voltage output terminal are electrically connected to a positive electrode of the battery lead clamp; a controlling terminal of the switch-controlling module is electrically connected to a controlled terminal; a voltage-detecting terminal is electrically connected to a positive terminal of the startup power supply; the switch-controlling module automatically detects the polarity connection status between the battery lead clamp and the startup power supply; the switch module is automatically connected when the connection is correct, so that the voltage of the startup power supply is output to the battery, thereby finishing the startup of the battery.