Authentication methods on smartphone are demanded to be implicit to users with minimum users’interaction. Existing authentication methods (e.g. PINs, passwords, visual patterns, etc.) are not effectivelyconsidering remembrance and privacy issues. Behavioral biometrics such as keystroke dynamics and gaitbiometrics can be acquired easily and implicitly by using integrated sensors on smartphone. We proposea biometric model involving keystroke dynamics for implicit authentication on smartphone. We first designa feature extraction method for keystroke dynamics. And then, we build a fusion model of keystrokedynamics and gait to improve the authentication performance of single behavioral biometric on smartphone. We operate the fusion at both feature extraction level and matching score level. Experiment using linearSupport Vector Machines (SVM) classifier reveals that the best results are achieved with score fusion:a recognition rate approximately 97.86% under identification mode and an error rate approximately 1.11%under authentication mode.