This　paper　presents　an　optimal　dispatching　model　for　the　charging　problem　of　massive　electric　vehicles　(EVs)　connected　to　the　power　grid,　takes　charging　discount　to　incent　EVs’　owners,　and　the　benefits　of　power　grid　and　electric　vehicle　aggregators　(EVAs)　are　both　token　into　consideration.　The　EVs’　cluster　charging　model　is　established　to　avoid　the　dimension　explosion　of　variables,　then　a　new　incentive　mechanism　based　on　charging　discount　is　proposed,　and　the　probabilistic　model　of　owners’　willingness　based　on　the　Weber-Fechner　Law　of　psychology　under　that　mechanism　is　constructed　to　estimate　the　willingness　of　EVs’　owners.　Then,　the　non-cooperative　Stackelberg　game　model　between　power　grid　and　EVAs　is　established　to　reduce　the　difference　between　the　load　peak　and　valley　while　balancing　the　benefits　of　EVAs　and　the　power　grid.　Finally,　an　example　based　on　the　presented　optimal　dispatching　model　considering　massive　EVs　is　put　forward,　the　result　of　example　verify　the　validity　and　practicality　of　the　proposed　model　in　reducing　the　peak-valley　difference　while　balancing　the　willingness　of　EVs’　owners　and　the　benefits　of　EVAs.　©　2021,　Springer　Nature　Singapore　Pte　Ltd.