The optical characteristics of one-dimensional metallodielectric photonic crystals (MDPC), constructed by inserting metal aluminum layers of certain thickness into the Si/SiO2 system, were studied theoretically with the transfer matrix method. The results show that the reflection efficiency can be enhanced considerably after the introduction of metallic layers, e. g. the rejection level of each period increased from 7.2 dB([Si(46 nm)/SiO2 (120 nm)]5) to 20 dB ([Si(46 nm)/SiO2 (60 nm)/Al (10 nm)/SiO2 (60 nm)]5). In addition, high omnidirectional reflection band with broader width can be obtained, e. g. bandwidth of 550 nm can be offered with [Si(46 nm)/SiO2 (60 nm)/Al (30 nm)/SiO2 (60 nm)]5. Rules of how the absorption, thickness and position of the metal layers affect the optical characteristics of the MDPC are also discussed. These MDPC structures may be used as compact-size, low-loss and broad-band optical reflectors.