A probabilistic algorithm is proposed for the problem of simultaneous robot localization and peopletracking (SLAP) using single onboard sensor in situations with sensor noise and global uncertainties over the observers pose.By the decomposition of the joint distribution according to the Rao-Blackwell theorem,posteriors of the robot pose are sequentially estimated over time by a smoothed laser perception model and an improved resampling scheme with evolution strategies; the conditional distribution of the persons position is estimated using unscented Kalman filter (UKF) to deal with the nonlinear dynamic of human motion.Experiments conducted in a real indoor service robot scenario validate the favorable performance of the positional accuracy as well as the improved computational efficiency.