Abstract Due to the fast improvement of information technology ,the application of internet is spreading in our society ,so is electronic commerce(EC).In hence ,many companies are starting to provide all kinds of services on the internet .In the stock market , stock brokers provide online stock trading service ,that enable the stock trading will not limited by time¡Bregions and people any more .However ,the internet has became a new way of investment. In Taiwan, there are more than 70 online stock brokers and one million investors that use online stock trading, and the volume of online stock trading is 5.87% to the total stock market. According to relative documents and some professional assessment mechanism, this study generalize 15 indexes of satisfaction of online stock trading questionnaires to query online stock brokers and investors, answers that we want to know are: what are the features of online trading investors? What are their responses of online stock trading? What are the factors that influence the indexes of satisfaction of online stock trading? What are the differences of satisfaction between online stock brokers and investors? The research outcome shows that investors which use online stock trading service is more younger and educated¡Bfrequency of trade is fewer¡Bthe amount of money is not much and the investors prefer self-service .And security of transaction is the primary factors that make the investors does not like online stock trading. Furthermore ,this study has generalized five primary factors that influence the satisfaction of online stock brokers and investors ,they are :¡uweb design¡v¡B¡unet speed ¡v¡B¡ufinancial specialty¡v¡B¡ucustomer services¡vand¡ufees¡v. And still other ,in the comparison of satisfaction between online stock brokers and investors , there is a gap in the aspect of ¡ufinancial specialty¡v,and by the further analysis ,there are gaps in the following index:¡urichness and quality of research reports¡v¡B¡usupply of other financial instruments¡v¡B¡uquery of customers information¡vand ¡usecurity of transaction¡v