This study focus on the spatial and temporal distributions and influence factors of dissolved (0.4 μm filtered) manganese (dMn) in the western Pacific Ocean during two cruises in October 2016 and November 2017. Two sections located in the 130°E and 20°N were investigated intensively to understand the vertical distributions of dMn in the western Philippine Sea and to trace the intrusion of Kuroshio to the South China Sea (SCS) and the potential impact of cross shelf transport of terrestrial materials from SCS to Kuroshio. The median concentrations of dissolved Mn in the surface layer of the western Philippine Sea were 2.5 nmol/L and 2.7 nmol/L in October 2016 and November 2017, respectively. The concentrations of dMn in the surface layer in November 2017 were significantly higher than that in 2016 (t-test, p < 0.05). High concentrations of dMn were observed in the south of the western Philippine Sea and the Luzon Strait, correlating moderately well with the low salinity. The vertical profiles of dMn during the two cruises were similar, with high concentrations in the surface water and decreased gradually with water depth. However, the high concentrations of dMn also occurred in the oxygen minimum zone (OMZ) in the stations located in the northern study area. The variation of dMn among two cruises mainly occurred in the upper waters, there was no significant difference in the water depths below 1000 m (t-test, p < 0.05). Relatively high concentrations of dMn and low salinity observed in the surface of the western Philippine Sea indicates the impact of terrestrial inputs from continent (e.g. South China Sea Surface Water etc.). The intermediate water column of northwestern Pacific Ocean was ultimately controlled by the North Pacific Intermediate Water (NPIW) based on the T-S diagram, with the characteristics of existing of the OMZ. A certain regeneration of dMn was also observed in the OMZ which was influenced by the decomposition and reduction of particles.