In　this　paper,　bulk　nanocomposite　permanent　magnets　are　prepared　by　spark　plasma　sintering　(SPS)　technique　using　melt-spun　powders　with　a　nominated　composition　of　Pr4.2Tb0.3Fe78B17.5.　Effect　of　processing　conditions　on　the　density,　microstructure,　and　magnetic　properties　of　the　magnets　are　studied.　Higher　sintering　temperature　improves　the　densification　of　the　magnets,　while　deteriorates　their　magnetic　properties　simultaneously　due　to　the　excess　crystal　grain　growth.　An　increased　compressive　pressure　leads　to　better　magnetic　properties　and　higher　density　for　the　magnets.　Magnet　possesses　a　Br　of　10.4　kGs　and　a　Hci　of　2.76　kOe　under　the　optimal　sintering　condition.　Observation　shows　the　microstructure　of　the　magnet　contains　fine　grains　with　an　average　size　of　about　20　nm.　The　fine　grain　size　in　the　microstructure　and　good　magnetic　properties　are　ascribed　to　the　rapidly　sintering　speed　and　high　compressive　pressure　of　SPS,　which　effectively　restrains　the　grain　growth　and　allows　the　formation　of　fine　crystalline　materials　with　full　dense　in　a　short　time.