The invention discloses a process for preparing caprolactam, which comprises the following steps: after mixing cyclohexanone and cyclohexane evenly, carrying out an oxamidine reaction to obtain a cyclohexane solution of cyclohexanone oxime; enabling the cyclohexane solution of the cyclohexanone oxime and oleum to react to generate a caprolactam sulfate solution, curing the caprolactam sulfate solution, then carrying out a neutralization reaction on the cured caprolactam sulfate solution and ammonia, afterwards separating the two materials to obtain a crude product of caprolactam and then carrying out extraction and water back extraction respectively to prepare a finished product. Because of the existence of a cyclohexane inert solvent, rectification and separation do not need to be carried out after the oxamidine reaction, and only a rearrangement reaction needs to be carried out after the water phase of a catalyst is separated, thereby saving a rectification device and the steam consumption; as a result, a caprolactam enterprise with an annual yield of a hundred thousand tons can save energy worth approximately 60000000 yuan every year and can also save the one-off equipment investment totaling 60000000 yuan, the technological process of caprolactam is simplified, the procedures of water washing, extraction, distillation and the like are reduced, the production period is shortened, and the annual yield is enhanced.