The invention relates to an integrated inertial sensor and a pressure sensor and a forming method thereof. The integrated inertial sensor and the pressure sensor comprise a first substrate, a second substrate and a third substrate; at least one or a plurality of conducting layers are positioned on a first surface of the first substrate; a movable sensitive element of the inertial sensor is formedby adopting the first substrate of a first region; the second substrate is combined with the surface of the conducting layer on the first substrate; the third substrate is combined with one side of the movable sensitive element of the inertial sensor formed by the first substrate, and the third substrate and the second substrate are positioned at two opposite sides of the movable sensitive element; and a sensitive thin film at least comprises the first substrate of a second region or one layer of the conducting layers. The integrated pressure sensor and the inertial sensor is formed by adopting the first substrate to form movable electrodes of the inertial sensor and adopting the first substrate or conducting layers to form the sensitive thin film of the pressure sensor, and have smaller volume and low cost, and have high reliability after being encapsulated.