Based on the principle of planar near-field measurement and theory on the spatial pattern of planar antenna arrays, a comprehensive investigation on the spatial pattern of planar antenna arrays tilting away from the planar near-field scanning plane is performed. An efficient computational algorithm on the near-field-far-field pattern in the plane determined by the rotation axis and normal line of the tilted array is developed. The parametric equations on the intersecting curve locus between the plane and unit directional sphere of the planar near-field scanning are thus derived. Consequently, the spatial pattern of the tilted antenna array based on the near-field data is calculated by fast Fourier transform technique, and at the same time a two-dimensional interpolating scheme to evaluate the pattern in the plane is developed. The capability, efficiency, and feasibility of this new algorithm are demonstrated by the good consistency of the calculated results with the numerical simulations and experimental measurements.