To obtain a kind of optical switch with strong switch effect,fa st response and simple structure,the liquid crystal optical switch based on dic hroic dye and polymer orientation is studied.By mixing dichroic dye and polymer into the vertically aligned liquid crystal,and irradiating it b y ul traviolet light under a bias voltage to cause the polymer orientation effect,th e liquid crystal cells with electrically controlled polarization characteristics were obtained,which were then assembled by the mode of 0°/90°of the polar ization angle to realize the liquid crystal optical switch.The insertion loss,ext inction ratio and response time of the liquid crystal optical switch were measur ed and compared.The measuring results show that the insertion loss of the liquid crystal optical switch can be less than 0.6dB,and the extinction ratio can be higher than 13dB.And with the method of polymer orientation,the hystere sis of vertically aligned liquid crystal layer can be eliminated with the result of th e response time lower than 20ms.Beyond this,by controlling the bias voltage of the polymer orientation process,the insertion loss or the response time can be further reduced alternatively.