Ripple is an important indicator to measure the power quality of DC distribution network. Ripple not only affects the power quality of the DC distribution network, but also jeopardizes the safe and stable operation of the power distribution system. The paper firstly introduces the basic concept of ripple and the definition of ripple-related parameters in DC distribution network, summarizes the current problem of measuring ripple with a harmonic way, gives the hardware requirements of ripple measurement and the selection of window time in ripple measurement, and then proposes different algorithms of low frequency ripple and high frequency ripple according to the characteristics of different frequency ripple in DC distribution network. Finally, the feasibility of the proposed method is verified through the measurement of low-voltage DC distribution network.