The invention discloses a control method of single cold-type air conditioner. The single cold-type air conditioner comprises a two-cylinder compressor, an outdoor heat exchanger, an indoor heat exchanger, a gas-liquid separator and a refrigerant radiator, wherein an air suction opening in a first cylinder is communicated with a first liquid reservoir; the exhaust volume ratio of a second cylinder to the first cylinder ranges from 1% to 10%; the gas-liquid separator comprises a gas outlet, a first connector and a second connector; the gas outlet is communicated with the second cylinder; a first throttling element with an adjustable opening degree is connected between the first connector and the outdoor heat exchanger in series; a second throttling element with an adjustable opening degree is connected between the second connector and the outdoor heat exchanger in series; the refrigerant radiator is connected between the first throttling element and the first connector in series, or is connected between the second throttling element and the second connector in series. The energy efficiency of the single cold-type air conditioner provided by the invention can be effectively improved.