Seeding method for synthesizing chabasite type molecular sieve with high silica/alumina ratio and application of the molecular sieve

The invention discloses a seeding method for synthesizing chabasite type molecular sieve. The seeding method comprises the following steps: evenly mixing alkaline silica sol and a template agent, slowly adding potassium hydroxide into the mixture, then adding sodium hydroxide, keeping on stirring, then slowing adding an aluminum sulphate water solution, adding a crystal seed in a chabasite crystalline phase, carrying out distillation to remove excess water, sealing, maintaining the temperature, stirring, shearing in a high speed so as to obtain uniform gel; and finally subjecting the gel to steps of crystallization, burning, and ammonium-exchange so as to obtain the finished product. The molecular sieve has the advantages of high silica/alumina ratio, high specific surface area, high MTO diolefin selectivity, and no pollution during the whole preparation process.