DNA with different length was solved into ultra-pure water, the conducing behavior of the suspension was investigated at varied temperature and DNA concentration. The electrical conductivity of the samples increased with the increment of temperature and concentration of the solution. In terms of the length, the short-strand DNA (less than 50bp) showed a better conducting capability than the long-strand DNA(more than 1000bp). The electrical conductivity of short-strand DNA arrives at 1.08 x 10(-3) S/cm at room temperature. The conductance of the two DNA samples became similar at high temperature as well as their uptrend when DNA samples were heated.