Both DC and AC conductance of Y-doped PbWO4 single crystal have been studied over a temperature range from ambient temperature to 160 ℃. Results of DC conductivity indicate that the carriers in PbWO4 in such a temperature ra nge are polarons other than ions, for a transition of polarons from energy band conduction to hopping conduction which characterized by a minimum of conductivity has been observed. AC conductivity obtained from admittance analysis is almost 3-orders higher than that of DC analysis, it ought to be mainly ascribed to the effect of dielectric. If conductivity and dielectric constant of a given system change together with frequency, AC measurement can only yield a total admittance spectrum, but is unable to separate conductivity spectrum from dielectric spectrum.