Mechanical properties of cement paste are indispensable and frequent requirement in structural analysis of concrete and other cement-based materials, and therefore the theoretical predictions have obtained considerable attention in the field of material engineering. Despite of being an active research area, available models for accurately predicting the mechanical characteristics of Ordinary Portland Cement (OPC) are limited, and which remains an imperative requirement in the cement industry. In this paper, a multiscale computational model is proposed for evaluating the basic mechanical properties of cement paste such as compressive strength and Youngs Modulus. The entire model consists of twophase: hydration model and multi-scale model. The hydration model which has been developed by chemical thermodynamic calculations using coupled PHREEQC is used to quantify the hydration products. Hence the multi-scale analytical scheme is used to predict the mechanical properties of cement paste. In this simulation, a unified procedure based on three hierarchal scales is developed, initiates from Calcium-silicate-hydrate (C-SH) matrix (consist of two types of C-S-H, monolayer water and gel porous) and progresses consequently up to the cement paste (consist of hydration products, porous and unhydrated cement). Finally, the validity of the proposed multi-scale model is verified with set of experimental data available in the literature. In conclusion, the scheme presented in this paper can accurately predict the Young’s modulus and compressive strength accurately with low average relative error.