The invention provides a preparation method of a CoSAPO-11 molecular sieve, relates to a preparation method of a molecular sieve and aims to solve the problems of a prepared molecular sieve such as low acid site density and unstable product quality in the prior art. The method comprises the following steps: 1, preparing a Co/X molecular sieve; 2, preparing an initial gel; and 3, crystallizing, and drying. According to the invention, the method combines ion exchange and isomorphous replacement, and realizes the modulation of two acid sites by changing the silicon-cobalt ratio; more acid sites can be formed in comparison with simply introducing cobalt and other heteroatoms; and higher stability is achieved. The invention is used for preparation of a CoSAPO-11 molecular sieve.