A barometer with multi-functions of measurement and depressurization has a body, an intake set, an exhaust set, a depressurizing set and a pressure meter. The intake set is mounted on a side of the body. The exhaust set and the depressurizing set are mounted on the body and aligning with the intake set. The pressure meter is mounted on a top surface of the body. The body has an inner channel communicating with the intake set, the exhaust set, the depressurizing set and the pressure meter. Thus, the functions of inflating, pressure measuring, depressurization and re-inflating can be accomplished by the barometer for eliminating the inconvenience of frequent installing and removing an inflation apparatus, a depressurization device and a pressure meter.