This invention relates to a kind of producing method for skelton rich-silicon molecular sieve with its crystal cell undergoing contraction. It is to take a strong acidic aqueous solution containing silicon, which after a regulation of its pH values, undergoes reaction with molecular sieve in water medium under a slow reaction condition. Said method has cheap and easily obtainable raw materials, and is simple in technological steps, and suitable for applying to various kinds of molecular sieves of either natural or artificially synthelized, opening size larger than 0.3 nm, and experimental formula of chemical composition M2/n.Al2O3.XSiO2.YH2O. The rich -silicon molecular sieve produced by said method has crystal cell contracted into 2.460-2.443 nm, with relative degree of crystallization more than 85%, and does not contain non-skelton aluminum in cystalline structure.