Abstract: The structure and application testing of a home-made portable mass spectrometer based on step-like electrode linear ion trap was introduced. The analyzer is step-like electrode linear ion trap, and the ion source is glow discharge electron impact ionization (GDEI) source and dielectric barrier discharge ionization (DBDI) source. The device is 10 kg weight，consuming less than 100 W, 33 cm in length, 20 cm in width and 20 cm in height, which can detect gas, solid and liquid. Volatile organic gases injected in the vacuum chamber from the membrane inlet interface, and ionized by GDEI. A discontinuous atmospheric pressure interface was assembled, with which atmospheric pressure ionization source was selected. By a DBDI source, the DDU and compound aminopyrine tablets was detected successfully and quickly.