Abstract: The present invention discloses a combined starting power supply, comprising a lead acid battery, a lithium battery and a lithium battery protection circuit, wherein the lithium battery protection circuit comprises a first input, a second input, a first output and a second output; a negative electrode of the lithium battery is connected to the first input, and a positive electrode of the lithium battery is connected to the second input; and a negative electrode of the lead acid battery is connected to the first output, and a positive electrode of the lead acid battery is connected to the second output. The combined starting power supply of the present invention increases the safety thereof by adopting a lithium battery; and the lithium-ion battery is always put in a safe working state by means of the lithium battery protection circuit during charging and discharging processes.