Aerial-Ground Person Re-Identification (AG-ReID) is a practical yet challenging task that involves cross-platform matching between aerial and ground cameras. Existing person Re-Identification (Re-ID) methods are primarily designed for homogeneous camera settings, such as ground-to-ground or aerial-to-aerial matching. Therefore, these conventional Re-ID approaches underperform due to the significant viewpoint discrepancies introduced by cross-platform cameras in the AG-ReID task. To address this limitation, we propose a novel and efficient approach, termed View-Invariant Feature Learning for Aerial-Ground Person Re-Identification (VIF-AGReID), which explores view-invariant features without leveraging any auxiliary information. Our approach introduces two key components: (1) Patch-Level RotateMix (PLRM), an augmentation strategy that enhances rotational diversity within local regions of training samples, enabling the model to capture fine-grained view-invariant features, and (2) View-Invariant Angular Loss (VIAL), which mitigates the impact of perspective variations by imposing angular constraints that exponentially penalize large angular deviations, optimizing the similarity of positive pairs while enhancing dissimilarity for hard negatives. These components interact synergistically to drive view-invariant feature learning, enhancing robustness across diverse viewpoints. We conduct extensive experiments on benchmark AG-ReID datasets, including CARGO and AG-ReID, to evaluate the effectiveness of our proposed method. Experimental results demonstrate that VIF-AGReID significantly outperforms existing state-of-the-art methods, achieving superior performance in cross-platform person Re-ID task.