NOVELTY - Preparing (1R,5R,6S)-3-((1R)-1-tert-butyl-dimethylsiloxy ethane)-1-methyl-2-diphenyl phosphoryl-oxy-carbapenem-2-en-3-carboxylic acid-p-nitrobenzyl ester (I), comprises e.g. adding 3-((R)-2-((2R,3S)-3-((R)-1-(tert-butyldimethylsilyloxy)ethyl)-4-oxoazetidin-2-yl)propanoyl)spiro(benzo(e)(1,3)oxazine-2,1'-cyclohexan)-4(3H)-one (II), tetrahydrofuran and water to a reactor, stirring at 0-10 degrees C, adding 30% hydrogen peroxide and magnetic solid base catalyst to the reactor, reacting for 1-2 hours, adding carbonyldiimidazole, reacting for 1-2 hours, adding thiophenol and reacting for 1-2 hours.    USE - The method is useful for preparing (1R,5R,6S)-3-((1R)-1-tert-butyl-dimethylsiloxy ethane)-1-methyl-2-diphenyl phosphoryl-oxy-carbapenem-2-en-3-carboxylic acid-p-nitrobenzyl ester.    ADVANTAGE - The method: exhibits simple operation and good technical performance; and is environmentally friendly.    DETAILED DESCRIPTION - Preparing (1R,5R,6S)-3-((1R)-1-tert-butyl-dimethylsiloxy ethane)-1-methyl-2-diphenyl phosphoryl-oxy-carbapenem-2-en-3-carboxylic acid-p-nitrobenzyl ester (I), comprises adding 3-((R)-2-((2R,3S)-3-((R)-1-(tert-butyldimethylsilyloxy)ethyl)-4-oxoazetidin-2-yl)propanoyl)spiro(benzo(e)(1,3)oxazine-2,1'-cyclohexan)-4(3H)-one (II), tetrahydrofuran and water to a reactor, stirring at 0-10 degrees C, adding 30% hydrogen peroxide and magnetic solid base catalyst to the reactor, reacting for 1-2 hours at room temperature, cooling, allowing to stand for 1 hour, removing aqueous solution formed at the bottom of the reactor, adding carbonyldiimidazole, reacting for 1-2 hours at 0-30 degrees C, adding thiophenol, reacting for 1-2 hours at 0-30 degrees C, cooling to 0-10 degrees C, adding a solution of sodium hexamethyldisilazane in tetrahydrofuran, reacting for 0.5-1 hours, adding a solution of bromoacetic acid in p-nitrobenzyl alcohol, reacting for 0.5-1 hours, adding diphenoxy acetyl chloride, reacting for 1-2 hours at 0-10 degrees C, adding phosphate buffer, filtering, washing the solid with a small amount of tetrahydrofuran, combining the tetrahydrofuran phases, washing with saturated salt water, drying using anhydrous sodium sulfate, concentrating under vacuum, and allowing to stand to obtain solid product (I). The magnetic solid base catalyst comprises magnetic hydrotalcite solid base. The amount of magnetic solid base catalyst is 1-20 mass% of (II).