The invention relates to a method for preparing a high silicon molecular sieve. The method comprises the following steps: circulating a molecular sieve along with inert carrier air under the carrying of inert carrier air flow and contacting the molecular sieve with gas-phase SiCl4 in a flowing sate, wherein the contact time of the molecular sieve and the gas-phase SiCl4 is from 10 seconds to 100 minutes. By using the method for preparing the high silicon molecular sieve in the invention, the continuous contact reaction of the molecular sieve and the SiCl4 can be achieved, and the contact time of the molecular sieve and the SiCl4 can be controlled through controlling the flow speed of the carrier air and the length of a tubular reactor, thus the contact reaction of the molecular sieve and the SiCl4 can be fully carried out in the tubular reactor.