It was experimentally investigated that competition between stimulated thermal scattering (STS) and stimulated Brillouin scattering (SBS) in absorbing liquids and that its phase conjugation characteristic in a master oscillator power amplifier (MOPA) system with a cell containing acetone dyed with small amounts of Cu(NO3)2 served as phase-conjugation mirror. It was showed that the stimulated thermal Rayleigh scattering (STRS) would predominate over the stimulated Brillouin scattering or stimulated thermal Brillouin scattering (STBS) by increasing the absorption coefficient of acetone, the gain of the stimulated thermal Rayleigh scattering increased and relative fluctuation of the output energy decreased with the absorption coefficient increased;under weaker pumping conditions stimulated thermal Rayleigh scattering would loss weaker phase information in original wavefront as same as stimulated Brillouin scattering did due to threshold effect; it is really possible to obtain high-quality phase conjugation by stimulated thermal Rayleigh scattering in absorbing liquid with appreciable absorption coefficient under appreciable pumping conditions.