A method for preparing a polycrystalline silicon rod using a mixed core means, comprising: (a) installing a first core means made of a resistive material together with a second core means made of a silicon material in an inner space of a deposition reactor; (b) electrically heating the first core means and pre-heating the second core means by the first core means which is electrically heated; (c) electrically heating the preheated second core means; and (d) supplying a reaction gas into the inner space in a state where the first core means and the second core means are electrically heated for silicon deposition, by which a deposition output is formed outwardly on the first core means or the second core means or both with a first deposition output or a second deposition output being formed thereby, respectively, at a reaction pressure in the range of 1-20 bar absolute and a reaction temperature in the range of 650 - 1,300 °C based on the surface temperature of the first deposition output or the second deposition output or both, wherein, in the step of pre-heating the second core means, the second core means is pre-heated to a temperature in the range of 350-1,000 °C with the first core means being electrically heated to a temperature in the range of 400-3,000 °C; wherein the resistive material is selected from: (i) a metal or an alloy comprising at least one metal element selected from the group consisting of tungsten, rhenium (Re), osmium (Os), tantalum (Ta), molybdenum (Mo), niobium (Nb), iridium (Ir), ruthenium (Ru), technetium (Tc), hafnium (Hf), rhodium (Rh), vanadium, chromium (Cr), zirconium (Zr), platinum (Pt), thorium (Th), lanthanum (La), titanium (Ti), lutetium (Lu), yttrium, ferrum (Fe), nickel (Ni), aluminum (Al) and a mixture thereof; (ii) a ceramic metal material comprising at least one component selected from the group consisting of molybdenum silicide (Mo-Si), lanthanum chromium oxide (La-Cr-O), zirconia and a mixture thereof; or (iii) a carbon-based material comprising at least one component selected from the group consisting of amorphous carbon, graphite, silicon carbide (SiC) and a mixture thereof. (a) installing a first core means made of a resistive material together with a second core means made of a silicon material in an inner space of a deposition reactor; (b) electrically heating the first core means and pre-heating the second core means by the first core means which is electrically heated; (c) electrically heating the preheated second core means; and (d) supplying a reaction gas into the inner space in a state where the first core means and the second core means are electrically heated for silicon deposition, by which a deposition output is formed outwardly on the first core means or the second core means or both with a first deposition output or a second deposition output being formed thereby, respectively, at a reaction pressure in the range of 1-20 bar absolute and a reaction temperature in the range of 650 - 1,300 °C based on the surface temperature of the first deposition output or the second deposition output or both, (i) a metal or an alloy comprising at least one metal element selected from the group consisting of tungsten, rhenium (Re), osmium (Os), tantalum (Ta), molybdenum (Mo), niobium (Nb), iridium (Ir), ruthenium (Ru), technetium (Tc), hafnium (Hf), rhodium (Rh), vanadium, chromium (Cr), zirconium (Zr), platinum (Pt), thorium (Th), lanthanum (La), titanium (Ti), lutetium (Lu), yttrium, ferrum (Fe), nickel (Ni), aluminum (Al) and a mixture thereof; (ii) a ceramic metal material comprising at least one component selected from the group consisting of molybdenum silicide (Mo-Si), lanthanum chromium oxide (La-Cr-O), zirconia and a mixture thereof; or (iii) a carbon-based material comprising at least one component selected from the group consisting of amorphous carbon, graphite, silicon carbide (SiC) and a mixture thereof.