For radar target tracking with nonlinear position and range rate measurements, a linear sequential filtering method based on the debiased measurement matrix of the converted pseudo measurement (DMM-LSF) is proposed. A novel and simple linear measurement matrix is constructed based on the relationship between the pseudo measurement and target's state vector. To estimate the involved unknown parameters in the measurement matrix, the filtering results from the linear position filter are utilized in the sequential linear filter, where a totally linear sequential filtering framework is formed. The measurement matrix estimation error is fully considered, which is incorporated into original converted pseudo measurement error and a new synthetical measurement error is formed. The statistic characteristics of the synthetical measurement error are deduced, resulting a debiased measurement matrix. Simulation results demonstrate the effectiveness of the proposed DMM-LSF algorithm. Compared with existing algorithms, the proposed one can achieve the best tracking performance for non-maneuvering and maneuvering target tracking in different scenes.