We propose a multitouch authentication algorithm based on minimum risk Bayes decision to improve the recognition rate of multitouch authentication on the smart phone. Firstly, authentication gesture sequences of each finger are classified by logistic regression of the mean dynamic time warping classifier. Then, based on the Bayes rules, we introduce a loss function to calculate the risk of local decisionmaking under the minimum risk Bayes decision fusion rules. Finally, we achieve global decisionmaking results according to the minimum risk Bayes decision fusion rules. Experimental results show that the leak alarm rate maintains satisfactory while the false alarm rate is effectively reduced by introducing minimum risk Bayes decision fusion rules into multitouch authentication, and the overall classification result is good.