The invention provides an oversaturated self-microemulsified progesterone composition. The oversaturated self-microemulsified progesterone composition consists of progesterone, non-natural plant oil, emulsifier, assistant emulsifier, stabilizer and the like. A preparation method of the oversaturated self-microemulsified progesterone composition comprises the following steps of: uniformly mixing the non-natural plant oil and the assistant emulsifier; dissolving the progesterone in the mixed liquid after being subjected to ultrasonic treatment; and adding the emulsifier into the mixture, and adding to dissolve or suspend the stabilizer in the mixture to obtain the composition. In the invention, as the progesterone is solubilized in 10-90nm oil-in-water microemulsion, dissolubility and dissolution rate of the progesterone in gastrointestinal fluid are increased; the microemulsion which is formed after oral administration envelops the progesterone in the non-natural plant oil and a surfactant layer so as to prevent the progesterone from being degraded by acid and enzyme in a gastrointestinal tract; and the stabilizer can be used for inhibiting progesterone crystals from precipitation during the dilution of the microemulsion to form oversaturated progesterone solution, so that more progesterone can be absorbed. The oversaturated self-microemulsified progesterone composition has the characteristics of low viscosity, stability in quality, high bioavailability, low toxicity, less side effect, short preparation time, low energy consumption and the like.