In this work, the solubilities of (D)- and (D,L)-penicillamine were first experimentally measured in the binary mixtures of ethanol and water. Then, the primary nucleation rate and various nucleation parameters of (D)-, (L)-, and (D,L)-penicillamine crystals were derived by the classical nucleation theory. Finally, molecular dynamics simulations were employed to investigate the intermolecular interactions and the nucleation kinetics through radial distribution function analysis and the Yasuoka-Matsumoto method, respectively. The simulation results were generally consistent with those of experiments. Under the same conditions, the enantiomeric crystals nucleated preferentially than the racemic, and the nucleation rate of the former was higher than that of the latter. Meanwhile, the appearance probability of (D)-penicillamine crystals was greater than that of (L)-penicillamine at low supersaturation levels, and both of them tended to be equal with the increase of the supersaturation level.