AstatisticalthermodynamictheoryoflinearproteinsolutionswasproposedwiththeaidofalatticemodelandappliedtotypeⅠantifreezeprotein(AFPI)solutions.ThenumericalresultsforseveralAFPIsolutionsshowthattheGibbsfunctionofthesolutionhasaminimumatacertainproteinconcentration,buttheproteinchemicalpotentialincreaseswithincreasingtheconcentration.TheinfluencesoftemperatureandproteinchainlengthontheAFPIchemicalpotentialwerealsodiscussed.Theevaluationforthecolligativedepressionofthefreezingpointconfirmsthattheantifreezeactionshouldberecognizedasnon-colligative.Thetheoreticaldeductionfortheconcentrationdependenceofthethermalhysteresisactivitycoincidesqualitativelywiththepreviousexperimentalandtheoreticalresults.