The fractal dimensions of earthquake precursor time series(resistivity and stress)which are gained from Changli ground resistivity station and ground stress station before and after the Tangshan earthquake (from 1971 to 1978) are calculated by the method of phase space reconstruction in this paper.The results show that the attractors of these two time series are of fractal dimension structure and the two different earthquake precursor attractos have the same diagnostic variation.It is also discovered that the ground resistivity is of multiple fractal dimension in different character scale,which is discussed in this paper.