Given the generally low quality of Production Development schedule baseline definition, an evaluation method of project schedule risk quantification based on Monte Carlo simulation under the conditions of resource constraints is proposed. Firstly, considering the resource constraints on the progress, an activity duration sampling method under resource constraints is proposed. Secondly, to study the probability distribution of project duration, a method to recognize the critical path to a project dynamically is proposed under the random change in the activity duration. Finally, examples will show that Monte Carlo simulation methods under resource constraints can assess the progress risk of IT project effectively and support the project decision-making.