简介：Inthispapertheleast-squaresmixedfiniteelementisconsideredforsolvingsecondorderellipticproblemsintwodimensionaldomains.Theprimarysolutionuandthefluxerareapproximatedusingfiniteelementspacesconsistingofpiecewisepolynomialsofdegreekandrrespectively.Basedoninterpolationoperatorsandanauxiliaryprojection,superconvergentH^1-errorestimatesofboththeprimarysolutionapproximationuhandthefluxapproximationσhareobtainedunderthestandardquasi-uniformassumptiononfiniteelementpartition.ThesuperconvergenceindicatesanaccuracyofO(h^r+2)fortheleast-squaresmixedfiniteelementapproximationifRaviart-ThomasorBrezzi-DouglasFortin-MarinielementsoforderrareemployedwithoptimalerrorestimateofO(h^r+l).