The invention mainly provides apremilast gel for injection to the articular cavity and a preparation method of the apremilast gel. According to the apremilast gel and the preparation method, polymer with the temperature-sensitive reverse gel property is adopted as a carrier material, and medicines are dispersed or dissolved in an aqueous solution of the carrier material. When the temperature is lower than the body temperature, a sample exists in the form of sol, and is injected into the body through a common syringe; when the temperature of the injected part rises to the body temperature, the sol is transformed into semi-solid gel, along with the slow dissolving of the carrier material, the medicines are released from the gel at the low rate, and the release of the medicines can last for several weeks to several months. The release ratio of the medicines can be realized by changing the variety, concentration, proportion and molecular weight of the gel material. The dosing interval of the gel is long, the preparation process is simple, the preparation process is mature, and the method is suitable for industrial mass production.