Abstract: The determinatlon of aromatic types in heavy distillates of petroleum by high ionizing voltage quadruple mass spectrometry with dlrect sample probe is described. The aromatic fraction is separated from heavy distillates of petroleum by sllica gel percolation and introduced directly into the EI ion source of the mass spectrometer by a direct insertion probe with a temperature programmed system. The influence of some conditions of mass spectrometer such as resolution, voltage and sample injection amount is discussed. The results show that veracity can be reflectcd by the intensity of the special mass of FC43 (standard sample).