In recent years, the photoluminescence and the photoconductivity of porous silicon were comprehensively studied. But the photoluminescence and the photoconductivity of porous polycrystalline silicon have not been wholely studied. In this paper, the results showed that luminescent property of the samples prepared by poly-crystal silicon wafers may be related to the defects on Si complexes surface, which can be proved by microwave-detected photoconductivity decay measurements. Furthermore, the luminescence of samples was disappeared under the external illumination, which may be related to the elimination of luminescent-centers. In addition, the conductivities of the samples were dependent on etched time and current density, and the large porosity of samples led to isotropic photoconductivity, which may be related to the change of energy band structure of the devices. (C) 2007 Elsevier B.V. All rights reserved.