The invention discloses a cold-start oil injection control method and a cold-start oil injection control system of a direct-injection gasoline engine, wherein the cold-start oil injection control method of the direct-injection gasoline engine comprises the following steps: acquiring an oil track pressure mode during cold start; injecting oil according to a first oil injection quantity if the oil track pressure mode is a low-pressure mode; otherwise, injecting the oil according to a second oil injection quantity, wherein the first oil injection quantity is larger than the second oil injection quantity. According to the method and the system disclosed by the invention, when the oil track pressure is in the low-pressure mode, an enough oil atomization quantity can be generated inside a cylinder so as to form ignitable mixed gas, so the gasoline engine can be started conveniently. When the oil track pressure is in a normal mode, formation of over-dense mixed gas can be weakened, so emission of tail gas particles can be reduced.