The invention relates to a gas intake system used for simulating insulating oil proportioning of a transformer. The gas intake system consists of more than two standard gas cylinders with different component contents, electromagnetic valves, a gas mass flow controller and a proportioning controller, wherein the standard gas cylinders are all communicated with a main pipeline provided with the gas mass flow controller through pipelines provided with the electromagnetic valves, the main pipeline at the right end of the gas mass flow controller is communicated with a gas inlet of an oil cylinder, the proportioning controller communicates with an upper computer provided with control software through Bluetooth or a USB (Universal Serial Bus) interface module, and the proportioning controller comprises a single-chip microcomputer control circuit, an I/O (Input/Output) driving circuit, an A/D (Analog/Digital) converter and a communication module. The gas intake system has the advantages of integrating automatic gas distribution, automatic gas intake and automatic flow control, saving time and labor, reducing artificial operation error and ensuring accurate flow control. The gas intake system meets the requirements on diversity and accuracy of standard oil sample preparation, and can provide an accurate proportioning system for similar qualitative and quantitative gas-liquid mixing.