The invention relates to an experimental method and a device for simulating the process that microcosmic remaining oil is extracted in a microcosmic simulation model under the condition of oil deposit high temperature and high pressure, researching feasibility of microorganism oil displacement technology in improving enhanced oil recovery after water drive, and carrying out visualized microcosmic oil displacement experimental research under the high temperature and high pressure experimental conditions, in particular to a high temperature and high pressure visual device for simulating microorganism oil displacement and a simulating method thereof. The device comprises a model clamp clamping a microcosmic visual model, a displacement system, a back pressure system, an annular pressure system, a pressure monitoring system, a temperature control system and an image collecting system. According to the device, temperature and pressure can be controlled easily, used space is small, safety performance is excellent, operation is simple, action mechanism of microorganism and petroleum hydrocarbon and starting mechanism of the microorganism on the remaining oil can be conveniently observed in a visualized condition, and the device has important significance on wide application and popularization of microcosmic experiments in oil industries.