A differential gear train (DGT) is a crucial component of a mechanical-hydraulic coupling mechanism. The transmission process generates oil churning losses, which significantly impact the overall transmission efficiency. Due to the complexity of DGTs and the unpredictability of lubrication reliability, traditional analysis of churning characteristics is inadequate. In this study, the moving particle semi-implicit (MPS) method is employed to analyze the effects of steady-state rotation speeds, dynamic rotation speeds, and oil filling heights on the oil churning characteristics of DGTs. The accuracy of the MPS method in predicting churning loss is illustrated by the average absolute percentage error of 6.4% obtained experimentally. It is concluded that: increasing the oil filling height improves lubrication reliability by 20.9%, but results in greater power loss. The lubrication reliability and power loss of DGTs with different output forms are mutually advantageous under different influencing factors. This paper helps to improve the lubrication reliability of DGTs.