Abstract: This paper presents a novel method for detection of asphaltene precipitation in residues, which is based on measurement of the electrical conductivity of the residua solution as a function of added precipitant, n-heptane. The maximum of the mass fraction normalized conductivity of the solution is found to be the beginning point of asphaltene precipitating. Then the ratio of n-heptane to residue when the maximum of the mass fraction normalized conductivity of the solution gained can be defined as the indication of the stability of residue. Four kinds of sample are studied by this method. DaQing VR and the maltene of Middle East VR are the most stable because they contain little n-C7 asphaltene. Middle East VR is more stable than Middle East AR for it contains less saturate. The result is consistent with the characteristics reflected from the saturate, aromatic, resin and asphaltene constitutes of them.