The invention relates to synthesis of organic chemicals, in particular to a process for directly synthesizing caprolactam by using cyclohexanone. The process comprises the following steps: 1) cyclohexanone and a titanium silicate molecular sieve (TS-1) with weight ratio of 2:1 are put in a reactor, then aqueous ammonia and hydrogen peroxide are simultaneously dropwise added in the reactor for stirring at the reaction temperature of 50 DEG C, and the reaction is kept for 60-180 min; and 2) the ionic liquid N, N, N-trimethyl-N-sulfobutyl-ammonium bisulfate is directly added to the reaction mixture after finishing dropping to react for 10-30 min to obtain the product of caprolactam, and the mol ratio of N, N, N-trimethyl-N-sulfobutyl-ammonium bisulfate: cyclohexanone: NH3: H2O2 is equal to 1-5:1:2:1.5. The process for directly synthesizing caprolactam by using cyclohexanone can perform two-step chemical reaction without a reactor, therefore, the operation is simplified and convenient; and the process conditions are mild, and the process is carried out under normal pressure and at the temperature of 40-60 DEG C.