Cold　sintering　process　(CSP)　is　a　new　method　to　prepare　ceramics　under　quite　low　temperature.　In　this　work,　two-step　CSP　under　different　pressures　was　employed　to　prepare　(K0.5Na0.5)NbO3　(KNN)　ceramics.　The　density　of　KNN　green　pellets　can　be　raised　by　enhancing　the　pressure　of　second-step　CSP.　Energy-dispersive　spectroscopy　reveals　the　composition　segregation　of　A-site　cations　in　large　grains.　The　dissolution　rate　of　K+　in　an　aqueous　medium　is　faster　than　Na+,　and　high　pressure　can　accelerate　K+　dissolution,　resulting　in　more　Na+　in　some　grains.　Besides,　the　diffusion　rate　of　Na+　in　grains　is　better　than　K+,　which　promote　the　grains　growth.　Finally,　the　piezoelectric　property　is　improved　even　with　low　ceramic　density　due　to　the　larger　grains,　which　possess　the　higher　performance　composition.　This　result　demonstrates　that　the　pressure　and　inhomogeneous　dissolution　of　alkali　metal　ions　among　CSP　play　an　important　role　in　grain　growth　and　piezoelectric　enhancement.