Abstract: The stability of line structure is influenced by under-excavation or over-excavation of rocks surrounding tunnels.It is of a great significance for understanding the surrounding rock stress and ensuring construction safety to research the law of under-excavation over-excavation for surrounding rocks of tunnels.This paper is based on the multi-resolution analysis of wavelet analysis and the statistical self-similarity on the surrounding rock under-excavation over-excavation for tunnels outline.It presents an approach of the fractal dimension estimation with wavelet analysis.The research results have shown that the suggested wavelet estimation method is satisfied by selection of appropriate wavelet functions and decomposition steps.The fractal dimension of overall outline,tunnel vault and tunnel wall have been calculated with wavelet analysis.The relationship between classes of surrounding rocks and the fractal dimension of tunnel outline is analyzed.The relationship between the stability of surrounding rocks and the fractal dimension of tunnel outline is also analyzed with combining with the actual situation.