A new contactless conductivity detector for microchip was developed.The electrode board and chip were independent of each other.The microfluidic chip was consisted of a 1.3 mm thickness of flat glass as cover and a substrate glass in which the same size of separation channel and reference channel were etched.The high frequency signal from signal generator was divided into two parts which were input into two pairs of the same electrodes in a printed circuit board subjected the separation channel and reference channel in the chip,respectively.When the analyte was passed the detection zone in separation channel,the conductivity difference between separation channel and reference channel were detected to be a peak of electropherogram.The experimental conditions,including excitation frequency and voltage,distance between two electrodes,and length of electrodes were investigated and optimized.Its feasibility and performance were demonstrated by analyzing inorganic ions.The optimized conditions were as follows:excitation frequency:100 kHz,excitation voltage:10 V(in peak to peak),distance between two electrodes:0.9 mm.Under the optimized conditions, the limit of detection reached to 12 μmol?L-1 for K+.This contactless conductivity detector was suitable for the analytical chip manufactured of ordinary thickness of flat glass as cover,and was also convenient in application for its independence between electrode board and chip.