Disclosed in the present invention are a capillary channel environmental sensor and a preparation method therefor. The capillary channel environmental sensor comprises a transfer cavity and at least one capillary channel. The cross sectional area of the transfer cavity is greater than the cross sectional area of the capillary channel, and one end of the capillary channel is connected with the transfer cavity; an elastic transfer diaphragm is provided between the transfer cavity and an external measurement environment. A positioned droplet is provided in the interior of the capillary channel, the positioned droplet is in tight contact with the inner walls of the capillary channel and the positioned droplet is in tight contact with a transfer medium. By means of the transfer cavity and the capillary channel that are connected to one another, because the cross sectional area of the transfer cavity is larger than the cross sectional area of the capillary channel, differences in volume between the transfer cavity and the capillary channel are used to transform a small displacement in a region of large volume into a large displacement in a region of small volume. Because the positioned droplet is provided in the capillary channel, and the capillary channel environmental sensor comprises a magnetic sensing element, the magnetic sensing element causes, on the basis of movement of the positioned droplet, the change in displacement through an intermediate variable to provide high-sensitivity and low-power detection.