Abstract: In order to reasonably compute the lateral pressure of a bulk-solid, the formula for the lateral pressure acting on the wall of a large squat silo was established based on the unified strength theory and the static equilibrium method, which considered the integrated effects of the friction between a silo and its granular material, the intermediate principal stress and overpressure caused by the conical pile top. The pressures predicted by Rankine formula, Coulomb formula and the solution obtained in this paper were compared with the available test results from published literatures. A parametric study is undertaken to investigate the influence of the unified strength theory parameter, internal friction angle and friction coefficient. The computational results by the proposed solution coincide quite well with test results. For the conical pile top of the stored bulk material, the pressures predicted by Coulomb formula are larger than the actual values, while those by Rankine formula are smaller. For the horizontal plane top, the pressures predicted by Rankine and Coulomb formulae are both in conservation. The effects of the unified strength theory parameter and internal friction angle are obvious, while the friction-coefficient effect is less significant.