The preparations and chemical properties of the sodium salts of O-ethyl N,N-diethyl-phosphoroamido-mono(or di)-thioacids (Ⅰ and Ⅱ) were reported. Ⅰ or Ⅱ reacted with alkyl halides to give the corresponding alkyl esters (Ⅴ, Ⅵ). By acidifying with diluted hydrochloric acid, Ⅰ and Ⅱ were converted into their corres-ponding acids (Ⅶ, Ⅷ) which, on treatment with alkyl iodide in the presence of or-ganic bases, diazomethane and cyclohexylamine, were transformed into the corresponding alkyl esters (Ⅸ),methyl ester (Ⅹ) and amide salts (ⅩⅠ) respectively. Reaction of Ⅱ with bromine or iodine gave the disulfide (ⅩⅡ),which was transformed into the phosphoro-amidothionochloridate (Ⅲ) by reacting with chlorine.