The invention discloses an assessment system used for water-optical complementation adjustment. The system comprises a data historical library, a data processing module and a result generating module, wherein the data historical library is used for reading power planning data, power actual data, voltage planning data and voltage actual data; the data processing module is used for calculating the power pass percent, the power adjusting speed, the voltage qualified rate and the voltage adjusting speed according to read data in the data historical library; the result generating module is used for generating a display curve according to the read data in the data historical library and/or the calculation result of the data processing module. As no precedent for a joint operation development water-optical complementation adjusting assessment system for a photovoltaic power station and a hydropower station exists in the prior art, the assessment system fills in the gap, and by analyzing the power and voltage after joint operation complementation coordinated power generation of the photovoltaic power station and the hydropower station and comparing an actual operation value and a power grid assessment required value, whether the actual value meets the assessment requirement of a power grid is correctly reflected.