Abstract: Detection of underwater high-speed moving targets faces challenges, such as long active detection cycles, discontinuous data, and passive detection failing to obtain target range, which makes it difficult to quickly and effectively calculate target motion parameters. To address these issues, a short-term motion analysis method for underwater high-speed moving targets based on a pseudo-linear Kalman filter(PLKF) was proposed. This method employed only one initial active detection at the beginning and was primarily a passive target motion analysis(TMA) method within the horizontal plane, supplemented minimally by active detection. Mathematical models were established, and iterative equations were provided. Based on the prior assumption that the target maintains constant-velocity motion for the majority of the observation time, simulation analysis was conducted under constant-velocity motion conditions. The root mean square error of the predicted trajectory was calculated using the Monte-Carlo method. Simulation results demonstrate that compared to bearing-only TMA using purely passive detection, this method enabled rapid convergence of the target motion parameter solution within a short time, with convergence achieved within no more than 10 seconds.