Preparation methods for ephedrine or pseudoephedrine and for ephedrine or pseudoephedrine intermediate

The invention discloses a preparation method for an ephedrine or pseudoephedrine intermediate. The preparation method comprises the following steps: with 2-chloropropionyl chloride and benzene as starting materials, carrying out the Friedel-Crafts reaction under the catalysis of Lewis acid so as to produce 2-chloro-1-phenyl-1-acetone; and reacting produced 2-chloro-1-phenyl-1-acetone with methylamine in an aprotic solvent so as to produce 2-methylamino-1-phenyl-1-acetone. The invention also discloses a preparation method for ephedrine or pseudoephedrine. According to the methods, phosphorus trichloride with severe pollution is not used anymore, and dangerous and expensive bromine is not used any longer; the Friedel-Crafts reaction and methylamination are carried out in the same solvent, so cost for public works is saved; and a safe, simple, cheap, green and novel process is provided for synthesis of ephedrine and pseudoephedrine.