A　Constant　Volume　Combustion　system　is　introduced　in　this　paper,　which　was　used　to　investigate　the　combustion　characteristics　of　gaseous　fuel.　In　the　system,　the　combination　of　methane　and　Carbon　dioxide　was　conducted　to　simulate　the　low　calorific　value　gas-biogas.　The　purpose　of　the　experimental　research　which　was　performed　on　the　system　is　to　study　the　effects　of　the　fraction　of　carbon　dioxide,　initial　temperature,　pressure　and　equivalence　ratio　on　the　combustion　characteristics.　The　experimental　results　shows　that　the　peak　pressure　decreases　with　the　fraction　of　the　carbon　dioxide　rising.　The　pressure　reaches　the　highest　value　at　the　stoichiometric.　The　peak　pressure　is　increased　with　the　initial　temperature　and　the　moment　that　occurs　is　advanced.　The　high　initial　pressure　leads　to　a　higher　peak　pressure.　©　2011　IEEE.