The invention provides a ground high-low pressure mixed gas-liquid separation system based on a multi-reservoir commingling production gas field. The ground high-low pressure mixed gas-liquid separation system comprises a gas inlet pipeline and a gas-liquid separator; an in-station block valve is arranged on the gas inlet pipeline; the outlet end of the in-station block valve is communicated with a high-low flow switching valve bank; the high-low flow switching valve bank is composed of a high-pressure flow control valve and a low-pressure flow control valve, the two of which are communicated in parallel to the outlet end of the in-station block valve. The ground high-low pressure mixed gas-liquid separation system is capable of simultaneously meeting the natural gas-liquid separation requirements in different production manners such as total high-pressure production, high-low pressure mixed production and total low-pressure production.