The investigation of nonlinear optical characteristics of ethanol solution doped with silver nanoparticles is presented. A large thermal-induced third-order nonlinear refractive index up to –1.941×10^?7 cm²/W is obtained from the mixed solution under 488-nm continue wave (CW) laser irradiation, which may result from surface plasmon resonance (SPR) enhancement effect of silver nanoparticles as well as high thermo-optic coefficient and low thermal conductivity of ethanol. Obvious spatial self-phase modulation and influence of thermal-induced negative lens effect are observed when a beam propagates through this solution, indicating promising applications such as optical limiting, beam flattening, and so on.