The present invention belongs to the field of enzyme-catalyzed preparation of glucosamine. Provided is a method for preparing glucosamine, especially a method for preparing glucosamine by in vitro enzyme catalysis. The method comprises : catalyzing the conversion of fructose-6-phosphate (F6P) and an ammonium salt into glucosamine-6-phosphate (GlcN6P) using glucosamine-6-phosphate deaminase (EC 3.5.99.6, GlmD); and catalyzing the dephosphorylation of GlcN6P using an enzyme capable of catalyzing the dephosphorylation to produce glucosamine (GlcN).