Electrophoretic　separation　in　short　microchannels　is　a　promising　way　for　rapid　analysis　of　biomolecules,　but　the　pressurized　laminar　flow　may　compromise　the　separation　efficiency.　In　this　work,　through　an　electric　field,　instant　formation　and　removal　of　a　solid　chitosan/beta-glycerol　phosphate　(CS/beta-GP)　hydrogel　within　microchannels　of　microchips　were　realized.　In　a　typical　cross-type　microchip,　the　CS/beta-GP　hydrogel　was　precisely　formed　in　the　separation　microchannel　within　15　s　of　the　application　of　a　voltage　of　2000　V.　Highly　efficient　separation　of　peptides　and　proteins　was　achieved,　and　theoretical　plate　numbers　of　0.6　to　1.5　x　10(6)/m　were　attained　for　proteins　in　120　s.　The　used　hydrogel　could　be　swiftly　removed　also　with　an　electric　field,　and　the　whole　procedure　was　achieved　on　a　standard　microchip　electrophoresis　device　with　no　extra　accessory　or　special　operation　required.