Polarity　effect　on　space　charge　distributions　can　be　found　within　high　voltage　extruded　polymeric　cables　under　DC　electric　fields.　In　order　to　reveal　the　physical　mechanism　of　the　polarity　effect,　a　numerical　model　considering　bipolar　charge　transport　with　recombination,　trapping　and　detrapping　in　polymeric　material　as　well　as　charge　injection　on　electrode　surfaces　was　introduced.　The　main　physical　parameters　affecting　the　asymmetry　space　charge　and　electric　field　distributions　at　cathode　and　anode　were　distinguished　by　parametric　analysis.　Then　the　model　was　applied　to　analyze　the　space　charge　and　electric　field　distributions　in　polypropylene　(PP)　under　an　uniform　DC　electric　field　and　compared　with　the　measured　data.　It　is　shown　that　the　mobility　and　the　detrapping　barrier　height　lead　to　the　asymmetrical　distribution　of　space　charge　in　PP,　while　the　mobility　and　the　injection　barrier　height　lead　to　the　asymmetrical　distribution　of　electric　field　in　PP.　The　results　can　provide　a　reference　for　the　regulation　and　control　of　polymeric　materials.　©　2016　Chin.　Soc.　for　Elec.　Eng.