This research presents a reliability assessment of composite steel-reinforced concrete beam with the input parameters are random variables. The uncertainty model was constructed based on the deterministic model of design composites steel-reinforced concrete beam according to Eurocode-4 by taking into account the randomness of some input parameters and Monte Carlo simulation. The Matlab-based calculation program allows the authors to perform digital investigation. This initial research result is a prerequisite for further research for other types of structures and taking into account the various random variables.