The lift-tilt configuration represents a prevalent architectural solution for electric vertical take-off and landing （eVTOL） aircraft. Consequently， systematic investigations into its general parameter design principles， optimization methodologies， and transition flight power characteristics are imperative to inform the design process. This paper proposes a performance analysis algorithm for lift-tilt configurations based on a longitudinal trim framework， wherein a lift rotor-horizontal tail fusion algorithm is developed to address the control redundancy issue. The predictive accuracy of the proposed algorithm is validated through comparison with experimental data. Subsequently， by integrating this performance algorithm with a weight estimation model， the influences of general parameter variations and battery energy density on empty weight and weight efficiency are quantitatively analyzed， yielding a set of general parameters that satisfy specific mission requirements. Furthermore， comprehensive parametric sweeps of power， angle of attack， and acceleration during the transition regime are conducted utilizing the proposed algorithm. Through detailed analysis of the computational results， the transition trajectory is qualitatively determined， and the energy consumption during the transition phase is minimized via acceleration optimization. Additionally， the variation trend of excess power throughout the transition process is characterized， thereby providing a systematic research framework and technical reference for the conceptual design and engineering development of lift-tilt eVTOL aircraft.