A coupled one-dimensional model was applied to Station Papa (50°N, 215°E), which is High Nitrate, Low Chlorophyll (HNLC) region. The physical model was based on the Regional Ocean Model System (ROMS), and the biogeochemical model used here was based on the Carbon, Silicate, and Nitrogen Ecosystem (CoSiNE) model. Observed seasonal cycles of ecosystem dynamics at Station Papa, such as maximum (minimum) chlorophyll-a concentration in summer (winter) in the upper ocean, were successfully reproduced by the model. Model simulations demonstrated that the temperature played an important role on the phytoplankton grow at high latitudes of the North Pacific. After taking into account the temperature effect on phytoplankton grow, the maximum concentration of chlorophyll appeared in July, which was consistent with the observation results. Therefore, the 1D model could successfully simulate the basic physical and ecological parameters of Station Papa. Based on this, a series of sensitivity analyses of iron-limitation were conducted in the model by reducing the potential maximum specific small phytoplankton and diatom growth rate. Within the iron-limitation experiments for small phytoplankton (diatom), the diatom population increased (decreased) and the small phytoplankton decreased (increased). In addition, total phytoplankton populations were mostly driven by the changes of small phytoplankton. Thus, the 1D physical-biogeochemical model could help to further investigate the ecosystem cycle in HNLC region and in the future, the iron cycle will be consisted in the 1D model. It is important to understand the major iron sources to the upper ocean, distributions and characters of different iron forms, the response of iron cycle to the change of ocean and atmospheric conditions in future in HNLC region.