The invention discloses a large liquid measure constant pressure displacement indoor physical simulation experiment device. The large liquid measure constant pressure displacement indoor physical simulation experiment device comprises a first automatic water adding device, a second automatic water adding device, an oil adding device, a first impurity removing device, a second impurity removing device, a pressure collecting device, an oil-water metering device and a rock core clamping device; control devices of the automatic water adding devices are provided with water adding control buttons and displacement control buttons; the automatic water adding devices comprise vacuum pumps. Two sets of the automatic water adding devices are adopted to work alternatively, enough water sources are provided for a large liquid measure constant pressure displacement experiment, and the experiment schedule cannot be influenced; the control devices serve as central systems in the whole process of water adding and displacement; on the one hand, the vacuum pumps provide power for water containers to feed water, on the other hand, dissolved gases of the water are pumped out through vacuum pumping, and therefore the influence of the dissolved gases of the water on the displacement experiment is reduced; the first impurity removing device is used for removing impurities of the water, and the second impurity removing device is used for removing impurities of oil; the oil-water metering device can measure the volume of the oil and water accurately, and errors are reduced.