A gravimetric method was used to determine the solubility of L-carnitine in different pure solvents and ethanol-acetone solvent mixture. The solubility in different pure solvents were then correlated by the modified Apelblat equation, lambda h equation and the modified van't Hoff equation, with the modified van't Hoff equation presenting the best consistence. Meanwhile, to illustrate the effect of ethanol or acetone on the change of the solubility, a new parameter defined as influence coefficient was introduced and the coefficient of acetone depending on temperature and molar faction of acetone was depicted. In addition, the changes for enthalpy, entropy and Gibbs free energy were calculated by the modified van't Hoff equation. It can be drawn that the changes for enthalpy and entropy in a solvent mixture decrease to a minimum before consequent increasing with increasing molar faction of acetone. Furthermore, the change for Gibbs free energy shows a linear relationship with natural logarithm of the solubility.