This paper focuses on the trusted vessel position acquisition using passive localization based on the booming low-earth-orbit (LEO) satellites.As the high signal-to-noise ratio (SNR) reception can-not always be guaranteed at LEO satellites,the re-cently developed direct position determination (DPD)is adopted.For LEO satellite-based passive localiza-tion systems,an efficient DPD is challenging due to the excessive exhaustive search range leading from broad satellite coverage.In order to reduce the com-putational complexity,we propose a time difference of arrival-assisted DPD (TA-DPD) which minimizes the searching area by the time difference of arrival mea-surements and their variances.In this way,the size of the searching area is determined by both geomet-rical constraints and qualities of received signals,and signals with higher SNRs can be positioned more ef-ficiently as their searching areas are generally smaller.Both two-dimensional and three-dimensional passive localization simulations using the proposed TA-DPD are provided to demonstrate its efficiency and valid-ity.The superior accuracy performance of the pro-posed method,especially at low SNRs conditions,is also verified through the comparison to conventional two-step methods.Providing a larger margin in link budget for satellite-based vessel location acquisition,the TA-DPD can be a competitive candidate for trusted marine location service.