The utility model discloses a compressed air quality detection device for appearance, include the sampling connecting pipe of being connected with the compressed air pipe way, wherein, an atmospheric pressure distribution unit is connected to the sampling connecting pipe, and atmospheric pressure distribution unit has the output of four ways trachea, and water content detecting element is connected through first governing valve to the output of first via trachea, and oil content detecting element is connected through the second governing valve to trachea output in second way, and dustiness detecting element is connected through the third governing valve to trachea output in third way, and a pressure balance gassing governing valve is connected on the fourth way, be provided with mass flow meter on the connecting line behind the first via and the second way governing valve respectively, one is detected the control unit and connects a plurality ofly respectively governing valve and mass flow meter. The device provided by the utility model can be at same sample point, with the measuring of carrying out water content, oil content, dustiness at one time, pressure distribution unit has guaranteed through the auto -Turning of bypass that water content measuring, oil content detect required gas flow's stability.