The utility model discloses a steam turbine baffle welding seam ultrasonic phased array detects with probe and scanning apparatus, seize the frame on both sides by the arms including the electronic watering can of water coupling, voussoir, ultrasonic phased array probe, dolly, encoder and voussoir, the frame is seized on both sides by the arms to the voussoir that the voussoir was assembled on being located the dolly, the ultrasonic phased array probe is installed on the voussoir, an electronic watering can of water coupling is intake to chew and is located the voussoir that is used for the electronic watering can of water coupling of water injection, the encoder is installed on the frame of dolly, install the wheel that contacts with the surface of measured workpiece on the dolly, the wheel record movement track of scanning apparatus on the measured workpiece that roll is together followed to the encoder to extremely control the instrument mutually rather than the supersound that links to each other with data transmission.