ABSTRACT In order to enhance the reasonableness of project scheduling optimization process, this paper puts forward a smart plant project scheduling optimization method based on hidden Markov algorithm. First, it introduces a kind of new method to cope with conflict. It refers to that once the conflict appears in the scheduling scheme, conduct status transfer aiming at the time schedule of the conflict instead of re-refining the starting time of the project to get another feasible time schedule, and enhance the calculation efficiency of the algorithm. Second, it takes the active and passive project scheduling problems as single and comprehensive problems for formulation, wherein, the target function includes a benchmark schedule cost and project response cost, and it finds out an optimal active and passive comprehensive project scheduling strategy; finally, it conducts modeling on the above project scheduling optimization problem by aid of Markov decision-making process, designs a kind of solution based on the dynamic planning of random graph. The experiment result shows that the method is effective in the convergence precision and calculation efficiency, and it demonstrates the reasonableness of the scheduling scheme by the means of Gantt chart.