To make up the deficiency of traditional ac electrohydrodynamics in explaining fluid flowing in opposite direction,a 3D point plane electrode system is devised to carry out microfluidic driving experiments,and the influence of electrochemistry and ac electro-thermal on microfluidic driving under low ac frequency has been analyzed.It is found that the flow direction under ac range of 10 Hz～3 MHz in the device is point to plane all the time,which is opposite to the prediction from theory of ac electro-osmotic(ACEO).The experiments verifies the leading role of electrochemical reaction under low ac frequency,and the result indicates that the leading influencing factor of the phenomenon of microfluidic under low ac frequency in point plane electrode system is electrochemistry.