The invention discloses a portable non-contact spacecraft sealed compartment on-orbit leakage ultrasonic detector, comprising a plurality of ultrasonic sensors, a laser distance measuring sensor, a housing, a DSP digital processing circuit, an amplification filter circuit, an LCD, and an alarm lamp. The detector uses the high-sensitive ultrasonic sensors and the high amplification-multiple low-noise amplification filter circuit, and can effectively detect weak leakage signals on a leakage upstream. The detector uses an independent rechargeable lithium battery to supply power, and the housing is in a pistol form, so that portable non-contact leakage detection is realized, and leakage determination and positioning are realized through the alarm lamp and the LCD. On an upstream end, the leakage detector can detect a leakage hole of [phi]0.3 mm to the minimum, and the farest detectable distance is larger than 500 mm, so that the detector can satisfy manned spacecraft on-orbit leakage detection requirements.