Electric conductivity and high voltage breakdown threshold of single plasma filament generated by femtosecond laser are spatio resolved measured. The results show that the resistance of the single filament is in a range of 280630 kcm after eliminating the contact resistance, and the breakdown threshold can be reduced down to ~50% of the original value in air. Furthermore, the variations of resistance and discharge threshold follow the same trend as that for the same part filament. The relation between breakdown threshold and resistance of the single filament is established.