An environmental sensor and manufacturing method thereof. The environmental sensor comprises: a substrate comprising at least one recess disposed at an upper portion of the substrate; and a sensitive film layer disposed above the substrate, comprising a fixed portion fixed on an end surface of the substrate and a bent portion configured to extend inside the recess. The bent portion and a side wall of the recess form a capacitor configured to detect a signal. The bent portion, fixed portion, and the recess form a closed cavity. A conventional capacitive structure configured on a substrate surface is changed to a capacitive structure of the environmental sensor vertically extending into the inside of the substrate, increasing a depth of the recess, and in turn, increasing a sensing area between two polar plates of the capacitor, significantly shrinking a coverage area of the capacitor on the substrate, and satisfying a requirement of a modern compact electronic component.