Thermal　rectification　effect　refers　to　an　asymmetric　heat　transfer　phenomenon　(namely,　the　amount　of　heat　flux　depends　on　the　direction　of　temperature　gradient).　A　two-segment　bar　made　of　two　materials　that　have　thermal　conductivities　with　different　temperature-dependence,　can　realize　the　thermal　rectification　effect.　In　the　present　paper,　we　propose　to　use　porous　structure　on　the　bulk　material　to　modify　the　thermal　conductivity　of　bulk　material.　It　is　found　that　the　thermal　rectification　effect　can　be　enhanced　by　the　porous　structure.　The　finite　element　method　and　effective　medium　approximation　are　used　to　analyze　the　influence　of　porosity　on　the　thermal　rectification　ratio　of　the　two-segment　system.　The　calculation　results　are　consistent　with　each　other.　Under　low　temperature　bias,　the　effect　of　the　porosity　is　weak,　while　its　influence　becomes　very　significant　when　the　temperature　difference　is　high.　Usually,　thermal　rectification　ratio　decreases　if　the　porous　structure　is　made　on　the　segment　whose　thermal　conductivity　increases　with　temperature　increasing.　If　the　porous　structure　is　made　on　the　segment　with　negative　temperature-dependent　thermal　conductivity,　an　optimal　porosity　can　be　found.　For　low　porosity,　the　forward　heat　flux　keeps　almost　unchanged　while　the　reverse　heat　flux　decreases　by　more　than　half,　and　the　thermal　rectification　ratio　can　be　increased　to　twice　or　more　than　thrice　that　in　the　case　of　no　porous　structure.　For　a　fixed　temperature　difference,　the　influence　of　porosity　on　the　thermal　rectification　ratio　increases　with　the　augment　of　the　power　exponent　value.