The invention discloses a novel process for synthesizing oxime through in-situ generated ammonia. The novel process is characterized in that ammonium salt and strong alkali and weak acid salt generate ammonia in situ, and then the ammonia reacts with ketone and hydrogen peroxide under catalysis of a titanium silicalite molecular sieve. The synthetic process has the advantages of simple oximation reaction, mild reaction conditions, few by-products, high product yield and environmentally friendliness. The synthesizing method is simple, an aftertreatment process is simple and convenient and has very strong operability and repeatability, and industrial production is promoted.