The use of piles to transfer compressive load to deep soil layers has always been considered by engineers. Due to the high cost of pile construction, estimating pile load with appropriate accuracy has always been considered by engineers because there is always uncertainty in theories, proposed relationships and physical and mechanical properties of soil. In geotechnical engineering, there are significant changes in the physical and mechanical properties of the soil that can affect the estimation of pile BEARING CAPACITY. In this study, the effect of uncertainty of various factors affecting the BEARING CAPACITY of concrete piles is examined from a probabilistic perspective, which include internal friction, adhesion, soil specific gravity, pile surface friction and length to pile diameter ratio. In this research, Monte Carlo analysis is used and the results of the first-order reliability analysis are compared with the analytical results based on Janbo theory. Validation of the method was also performed using the Monte Carlo simulation method in RT software. The effect of random parameters on the reliability index shows that the internal friction angle is the main factor on the compressive BEARING CAPACITY of the pile. The results of this study also show that the use of first-order methods for sensitivity analysis and reliability analysis may not be accurate, so the Monte Carlo simulation method is proposed.