Abstract: Based on the experimental result of the electro-optic property of twsited nematic liquid crystal （TN-LC）, a deeper study of the TN-LC electro-optic response times is carried out. And a new method to approach the critical driving voltage is introduced by understanding the response times under different driving voltages.

Key words: twsited nematic liquid crystal （TN-LC）, electro-optic curve, response time, critical voltage