Abstract: With increasing number of residential PV units, voltage violations, voltage fluctuations and unbalance issues are becoming outstanding in medium-voltage distribution networks（MVDNs） and low-voltage distribution networks（LVDNs）. This paper investigated the multi-objective coordinated control strategy between the two voltage levels. Firstly, based on the analysis of communication and computation conditions, a hierarchical coordinated architecture was proposed featuring centralized control in the MVDNs and distributed control in LVDNs. Secondly, in the MVDNs, a centralized control model based on three-phase optimal power flow was developed in the timescale of minutes with multi-objectives to minimize power losses and unbalance, setting P/Q of distribution generations, static var generations and PCC as controllable variables. Moreover, in the LVDNs, a distributed control model considering multi-objectives was proposed in the timescale of seconds to track reference P/Q at PCC given by the MVDN and mitigate its fluctuations, improve unbalance and avoid voltage violations. Coordination strategy between these objectives was also added to the distributed control model. Case studies verified that the proposed strategy can coordinate LV ESSs and PV inverters to provide flexibility for the MVDN, and decrease more than 95% power fluctuation rate（average fluctuation rate not more 0.5%）. Meanwhile, voltage violations and unbalance were all improved in the MVDNs and LVDNs.