Background: Microwave imaging is widely used in many areas involving non-destructive testing, biomedical imaging, radar detection and imaging, etc. However, there is a lack of microwave 3D imaging methods with lateral and depth super-resolution. Objective: We propose a microwave near-field 3D super-resolution imaging method based on the near-field scanning microwave microscopy (NSMM) technique, enabling lateral and depth super-resolution simultaneously. Methods: A resonant-cavity probe is designed to scan the first group of step samples to establish a linear equation between the phase of the normalized reflection coefficient (NS11) and the tip-sample distance ( Δ H ). The second group of samples is scanned at the resonance frequencies corresponding to Δ H , realizing the layer-by-layer imaging of the letter patterns. Finally, we have calculated the height information through the fitted linear equation and reconstructed the second group of step samples with letter patterns. Results: The 3D reconstruction of the second group of step samples with letter patterns is completed. The depth variation of the step and the height of the letter patterns are 200 μ m (~ λ/570), which can be identified approximatively through experiments. And the letter patterns with a lateral width of 720 μ m (~ λ/160) are resolved. Conclusion: The experimental results show that our method has good feasibility in realizing microwave 3D imaging with depth and lateral super-resolution. [ABSTRACT FROM AUTHOR]