A　target　can　be　positioned　by　wireless　communication　sensors.　In　practical　system,　the　range　based　sensors　may　have　biased　measurements.　The　biases　are　mostly　constant　value,　but　they　may　jump　abruptly　in　some　special　scenarios.　An　on-line　bias　change　detection　and　estimation　algorithm　is　presented　in　this　paper.　This　algorithm　can　detect　the　jump　bias　based　on　Chi-Square　Test,　and　then　estimate　the　jump　bias　through　Modified　Augmented　Extended　Kalman　filter.　The　feasibility　and　effectiveness　of　the　proposed　algorithms　are　illustrated　in　comparison　with　the　Augmented　Extended　Kalman　filter　by　simulations.