In this work, polyaniline co-doped with (IS)-(+)-10-camphorsulfonic acid (D-CSA) and Ni2+ was synthesized via in situ polymerization. The structure, conductivity and electromagnetic parameters of the resulting polyaniline were characterized by FTIR, SZ82 digital multimeter and AV3618 network analyzer. The conductivity of polyaniline at room temperature increases with increasing of Ni2+ loading. Moreover, the resulting polyaniline co-doped with Ni2+ displays obvious magnetic loss at the microwave frequency. So, we suppose that this conducting polymer can be used as microwave absorbing material with wide-range and good effect.