There are uncertainties in engineering cost activities for engineering project management. Risks in engineering cost surely bring forth risks in engineering cost control. Only when the risk factors in engineering cost activities are scientifically analyzed the “three excess” phenomena can be avoided. By comprehensively using risk management and mathematical statistics theory, the author sets random sampling functions for the probability distributions of the uncertain factors impacting engineering cost, inputs the random samples into the cost-computing equations, simulates the uncertain factors impacting cost in specific projects using Monte Carlo simulation and the Crystal Ball software, and then obtains simulation results for cost. Next the author performs statistics analysis on the simulation results and obtains a risk value for cost. By analyzing this value the author provides reference comments for risk management of project cost, so as to elevate the accuracy for cost control.