The invention discloses a preparation method of 
mulberry leaf metallothionein. The preparation method of the 
mulberry leaf metallothionein is completed through the six steps of 
mulberry leaf protein extracting, 
protein fusion vector expression constructing, biomembrane separating, orientated 
metal ion releasing, 
enzyme digestion eluting and purifying, refining and freeze-
drying. A 
protein source of the mulberry leaf 
metallothionein is extracted and separated from pure plants, the 
plant protein resources are fully utilized, and compared with MT raw materials from other sources, the advantages of being reliable in 
raw material source, simple in extraction process, low in cost, green, safe and the like are achieved; when concentrated liquid protein is induced with 
metal ions, a metallic element which is necessary for a 
human body is selected as a fusion vector expression body, and therefore the target product can be stably expressed in a soluble and high-yield mode; the 
target protein and quantitative releasing of the 
metal ions can achieve classified expression to obtain purified MT 
protein molecules with the different structures; the extraction process cycle is short, the handling capacity is high, and the target product obtained through reacting has the advantages of being high in recycling rate, few in loss, high in purity, free of secondary 
pollution and the like.