The invention discloses a preparation method and application of long-acting metal antirust liquid. The preparation method comprises the following steps: firstly, mixing glyceryl monostearate, pentaerythritol oleate, diethanolamine borate, triethanolamine, dodecenylsuccinic acid and ethylenediamine tetraacetic acid; adjusting a pH value in a reaction kettle and then carrying out stirring reaction; in addition, carrying out ball milling treatment on aluminum oxide, castor wax, sodium cetostearyl sulphate and lauramide sodium ethylsulfate, then adding 1,3-dibutyl thiourea, dipropylene glycol monomethyl ether and dipropylene glycol mono butyl ether and carrying out stirring reaction; mixing the components of two parts and then carrying out internal mixing; finally, reacting in the reaction kettle to obtain a finished product. According to the preparation method, the prepared long-acting metal antirust liquid has the advantages that the prepared long-acting metal antirust liquid is long in antirust period; the antirust liquid is stable in own character, can meet the requirements of industry, and has no toxicity and a good application prospect. Meanwhile, the invention also discloses a specific application range of the preparation method.