The invention discloses an aluminosilicophosphate molecular sieve SAPO-34 and a preparation method thereof, comprising: a) mixing silicon resource, organic amine template agent and fluoride accessorial template agent to form an alkaline mixture with the pH value being 8.5-9.5; b) orderly adding aluminum resource and phosphorus resource into the alkaline mixture, and adding water; crystallizing precursor solution keeps the pH value of the alkaline crystallizing liquid between 7.5 and 8.5 in the process of mixing; and c) crystallizing the alkaline crystallizing liquid to obtain the aluminosilicophosphate molecular sieve. The invention greatly improves the yield of aluminosilicophosphate molecular sieve SAPO-34; and the prepared aluminosilicophosphate molecular sieve SAPO-34 has better performance of catalytic activity, higher productive selection as well as longer lifetime of catalyst in the reaction of preparing olefin by using oxygenated chemicals.