Abstract: This paper studies the phase behavior of microemulsion by using N263 as surfactant alcohols as cosurfactant and kerosene as oil phase. We focus the study on the effects of surfactant concentration, co-surfactant kinds and concentration, inner water phase salinity and pH value, on water content of the microemulsion the stability of micro-emulsion is also investigated by measuring the its conductivity. The results shows the microemulsion stays stable and the water content can reach to about 15% under the following conditions: N263 concentration is 10%; isoamyl alcohol concentration is 25%; inner water phase concentration is 0.4mol/L NaCl+0.2mol/ L NaOH; temperature is 35℃; kerosene used as oil phase.