The invention discloses a 
salt lake lithium extraction device based on the 
ion concentration difference polarization effect. The device comprises a 
main channel, a 
lithium sodium solution cavity and abuffer liquid cavity; an 
ion selective block is arranged in the middle of the 
main channel, one or multiple parallel micron channels are formed in the 
ion selective block in the pipeline direction, the ion selective block is made of a 
cathode selective permeable membrane material, the 
cathode selective permeable membrane material has electrical 
conductivity and only allows negative ions to pass through, however, positive ions and water cannot pass through. The difference of electrophoretic mobility of different positive ions is used for enriching 
lithium ions on the position closest to the position nearby the ion selective cylindrical block, then, sodions and 
magnesium ions are selected, and 
potassium ions are not enriched in the channels. Therefore, micron holes are punched in the frontchannel wall close to the ion selective cylindrical block, enriched lithium ions are drained to the lithium 
sodium solution cavity, and are guided out to a finished product lithium 
sodium solution pond from a lithium sodium solution outlet. The characteristic that the concentration of the sodions is obviously larger than the 
magnesium ions and lithium ions, and the enriching area of the sodions isbetween 
magnesium and lithium, sufficient separation of the magnesium ions and the lithium ions is achieved.