In recent years, with the rapid development of DC technology and the increasing capacity of wind power connected to the power grid, wind power systems integrated into DC distribution systems have become an effective mode of absorbing new energy generations. Therefore, the oscillation problem between the key equipment of the wind power grid-connected system is worthy of attention. This paper constructs a small disturbance stability model for a direct-drive wind power system in the DC distribution system, and the oscillations relationship of key equipments are obtained by the eigenvalue and modal analysis method. Then, the influences of synchronous motor parameters, PLL control parameters and DC/DC converter control parameters on the operation mode of system, and dynamic interaction between wind turbine side and grid-connected converter are obtained based on the proposed model. It is helpful to analyze the multi-time scale oscillation in DC distribution system.