The target characteristic research of micro-laser plasma thruster (μLPT) is introduced, and propulsion performance of different target structures and doped concentrations is discussed. Results indicate that there can be an optimum impulse coupling coefficient for the confined target. The thinner the target is, the bigger the optimum impulse coupling coefficient is, the lower the laser energy is, and the higher the specific impulse is. The absorption of laser energy can be intensified by the doped carbon, ablation efficiency can be enhanced, and there might be still other energy dissipation enhanced, and that can result in the decrease of impulse coupling coefficient.