Novel　hierarchical　microspheres　of　aggregated　silicon　nanoparticles　(p-Si　microsphere)　with　nanometre　gaps　have　been　synthesized　through　reverse　microemulsion　in　combination　with　a　modified　magnesiothermic　reduction　approach　using　silica　(similar　to　200　nm)　as　the　precursor.　The　hierarchical　porous　structure　of　p-Si　microspheres　is　composed　of　abundant　intergranular　gaps　(100-200　nm)　in　the　interconnected　nanosized　Si　particles,　along　with　ultrafine　Si　nanosized　grains　(similar　to　5　nm)　and　intragranular　voids　formed　in　interconnected　nanosized　Si　particles.　The　hierarchical　microspheres　of　aggregated　Si　nanoparticles　possess　a　high　specific　surface　area　of　136　m(2)　g(-1)　and　can　achieve　a　high　tap　density　of　0.3　g　cm(-3).　Such　a　novel　microstructure　with　a　large　surface　area　and　void　gaps　between　interconnected　Si　nanoparticles　can　accommodate　the　volume　change　of　Si　during　the　lithium　ion　(Li+)　alloying/dealloying　process.　Meanwhile,　the　mesoporous　structure　facilitates　Li+　penetration　into　the　nano-Si　grain　interface,　significantly　shortening　the　Li+　diffusion　pathway　as　well　as　enhancing　the　heterogeneous　reaction　sites.　Such　hierarchical　microspherical　Si　anodes　demonstrated　excellent　cycling　stability,　delivering　reversible　capacity　of　845　mAh　g(-1)　after　200　cycles　at　0.2　Ag-1　and　rate　performance　with　a　high　reversible　capacity　of　681　mAh　g(-1)　at　1　Ag-1　with　97%　of　initial　capacity　retention.