The　quantitative　evaluation　of　the　impact　of　drought　on　crop　yield　is　one　of　the　most　important　aspects　in　agricultural　water　resource　management.　To　assess　the　impact　of　drought　on　wheat　yield,　the　Environmental　Policy　Integrated　Climate　(EPIC)　crop　growth　model　and　daily　Standardized　Precipitation　Evapotranspiration　Index　(SPEI),　which　is　based　on　daily　meteorological　data,　are　adopted　in　the　Huang　Huai　Hai　Plain.　The　winter　wheat　crop　yields　are　estimated　at　28　stations,　after　calibrating　the　cultivar　coefficients　based　on　the　experimental　site　data,　and　SPEI　data　was　taken　11　times　across　the　growth　season　from　1981　to　2010.　The　relationship　between　estimated　yield　and　multi-scale　SPEI　were　analyzed.　The　optimum　time　scale　SPEI　to　monitor　drought　during　the　crop　growth　period　was　determined.　The　reference　yield　was　determined　by　averaging　the　yields　from　numerous　non-drought　years.　From　this　data,　we　propose　a　comprehensive　quantitative　method　which　can　be　used　to　predict　the　impact　of　drought　on　wheat　yields　by　combining　the　daily　multi-scale　SPEI　and　crop　growth　process　model.　This　method　was　tested　in　the　Huang　Huai　Hai　Plain.　The　results　suggested　that　estimation　of　calibrated　EPIC　was　a　good　predictor　of　crop　yield　in　the　Huang　Huai　Hai　Plain,　with　lower　RMSE　(15.4 %)　between　estimated　yield　and　observed　yield　at　six　agrometeorological　stations.　The　soil　moisture　at　planting　time　was　affected　by　the　precipitation　and　evapotranspiration　during　the　previous　90 days　(about　3 months)　in　the　Huang　Huai　Hai　Plain.　SPEIG90　was　adopted　as　the　optimum　time　scale　SPEI　to　identify　the　drought　and　non-drought　years,　and　identified　a　drought　year　in　2000.　The　water　deficit　in　the　year　2000　was　significant,　and　the　rate　of　crop　yield　reduction　did　not　completely　correspond　with　the　volume　of　water　deficit.　Our　proposed　comprehensive　method　which　quantitatively　evaluates　the　impact　of　drought　on　crop　yield　is　reliable.　The　results　of　this　study　further　our　understanding　why　the　adoption　of　counter　measures　against　drought　is　important　and　direct　farmers　to　choose　drought-resistant　crops.　©　2016,　ISB.