The Steklov eigenvalue problem is a classical eigenvalue problem in spectral geometry. In this paper, we study the first (non-trivial) Steklov eigenvalue \(\sigma _2\) of graph G with boundary B. Let D be the maximum vertex degree. Using metrical deformation via flows, we first show that \(\sigma _2 = \mathcal {O}\left( \frac{D g^3}{|B|}\right) \) for graphs of orientable genus \(g > 0\) if \(|B| \ge \max \{3 \sqrt{g},|V|^{\frac{1}{4} + \epsilon }, (9 \sqrt{g})^{\frac{1}{2}+\frac{1}{8\epsilon }}\}\) for some \(\epsilon > 0\) . This can be seen as a discrete analogue of Karpukhin’s bound. Secondly, we prove that \(\sigma _2 \le \frac{8D+4X}{|B|}\) based on planar crossing number X. Thirdly, we show that \(\sigma _2 \le \frac{|B|}{|B|-1} \cdot \delta _B\) , where \(\delta _B\) denotes the minimum degree for boundary vertices in B. At last, we compare several upper bounds on Laplacian eigenvalues and Steklov eigenvalues.