Provided a complex of formula is [3-((1S, 3R)-1-biphenyl-4-ylmethyl-3-ethoxycarbonyl-1-butylcarbamoyl) propionate- (S)-3'-methyl-2'- (pentanoyl {2''-(tetrazol-5-ylate) biphenyl-4'-ylmethyl}amino) butyrate] 6·XCa2+·YNa+·ZH2O, wherein X=1-3, Y=12-16, Z=9-18, and 2X+Y=18, and represented by formula (I). Also disclosed are the method of preparing the complex and the method of treating chronic heart disease using a medicament comprising the complex.