The invention relates to the technical field of deep-cooling oxygen preparation and discloses a medical care gas liquid oxygen inverse injection type preparation and supply device and a preparation method thereof. The device comprises a hot end system (15), a cold end system (16) and a reserve system. One end of a liquid oxygen inverse injection pipeline (17) is connected with a liquid oxygen storage tank (11). The other end of the liquid oxygen inverse injection pipe (17) is connected with the bottom of a rectifying tower (8). The bottom of the rectifying tower (8) is connected with a main condensation evaporator (9) through a liquid oxygen pipeline (22). A stream of air treated through the hot end system (15) and liquid oxygen in the main condensation evaporator (9) conduct heat exchange. During the technological process, the device can provide oxygen meeting air pressure for a hospital by improving the operating pressure of the rectifying tower without a liquid oxygen pump and provides required cold energy through the liquid oxygen inverse injection process without an expansion machine for refrigeration. The medical care gas liquid oxygen inverse injection type preparation and supply device is simple in structure, fewer in amount of power units, reliable in operation and low in cost.