The invention provides a flexible micro pressure sensor and a preparation method thereof, and belongs to the field of micro pressure sensor preparation. The flexible micro pressure sensor comprises a flexible substrate, a conducting layer and a flexible coupling electrode, wherein the flexible substrate is of a right square pyramid micro structure, the conducting layer is positioned on the flexible substrate, the flexible substrate is polydimethylsiloxane dimethyl silicone polymer with the right square pyramid micro structure, the conducting layer is a single-wall carbon nanometer tube, and the flexible coupling electrode is polyethylene glycol terephthalate with an indium tin oxide conducting layer. A lower electrode with the right square pyramid micro structure is adopted, and the deformation of the right square pyramid micro structure is very obvious under the pressure effect, so that the response of the sensor to micro pressure is more sensitive; the single-wall carbon nanometer tube is adopted as the conducting layer, and is transparent for visible light, in addition, the sensor cannot be easily damaged in the stretching or bending process, and the stability is good; the polydimethylsiloxane dimethyl silicone polymer is used as a lower electrode substrate, the flexibility is good, and the bending and the stretching can be realized.