High penetration of renewable energy brings economic and environmental benefits to the grid, but also causes challenges to the distribution system flexibility due to its uncertainty. As a new variable load, electric vehicles (EVs) can increase system's flexibility through interactions with the grid and promote the consumption of renewable energy. This paper studies the flexibility evaluation of distribution system considering the interaction between EVs and the grid. Firstly, the charging and discharging control strategies of EVs have been analyzed to reduce the impact of renewable energy output fluctuations on the distribution system flexibility, such as the G2V (Grid to vehicle) and V2G (Vehicle to grid) modes. Secondly, the battery capacity, driving plan, and transportation network are modeled to study the impact of the EVs connected to the grid on the distribution system flexibility. Thirdly, the flexibility evaluation method of distribution network is proposed based on the feasibility analysis of uncertain region. Finally, the analyses of the example show that the proposed method can realize the evaluation of the time series flexibility of the distribution system, which proves the effectiveness of the method proposed in this paper. INDEX TERMS ST time span, such as 24 。 the Hadamard product a, b, c the operation cost coefficients of the thermal power unit F the flexibility evaluation index Pg,t the output of the thermal power unit at time t d the element value corresponding to the uncertain variable n in the time series direction matrix D at time t λpv the cost coefficient of PV output curtailment valuend the normalized deviation value Ppvc,t the planned PV output curtailment x the decision variable in the optimization process xt, yt, zt the 0-1 variable representing the status, start and stop of the thermal power unit Pi, Qi injected active power and injected reactive power at node i respectively. Pg,min, Pg,max the lower and upper limits of thermal power unit output Ui, Uj voltage amplitude of node i and j Rramp the ramp rate of thermal power unit Gij, Bij conductance and susceptance of branch ij , the predicted output of PV θij voltage phase angle difference between node i and j PV,t the charging power of the grid to the electric vehicle V at time t Il the branch l current amplitude Nev the total number of EVs the maximum value of branch l current amplitude PVmin,t, PVmax,t the minimum and maximum charging power of electric vehicle V at time t Ui he voltage amplitude of node i PL,t the total load demand except for electric vehicles Uimax, Uimin the upper and lower limits of node i voltage amplitude DN the set of distribution network nodes PREi,t, QREi,t the active power and reactive power of renewable energy output at node i and time t