Splines are widely used in aeronautic applications to transfer rotation and torque due to their simplicity, reliability, and high load-carrying capacity. However, misaligned splines often suffer contact stress concentration, tooth surface sliding, and even further fretting wear and fretting fatigue failure. One practical way to prevent fretting wear and fretting fatigue is to relieve contact stress concentration and reduce tooth surface slip. This paper focuses on revealing the performances in relieving contact stress concentration and reducing tooth surface slip of two new types of splines (i.e., crowned circular-arc metal spline and circular-arc composite spline) compared to the conventional involute spline. To this end, this paper proposed finite element models for these three types of splines to predict contact stress and sliding. The influence of angular misalignment is analyzed. The results indicate that the composite spline exhibits a lower level of contact stress, helping to mitigate stress concentration. The crowned circular-arc metal spline demonstrates lower contact stress levels than the conventional involute spline under larger misalignment angles (greater than 0.135° in this study). Furthermore, the crowned circular-arc metal spline’s contact sliding is unaffected by misalignment angles.