The study considers cash flow and proposes an profit optimization model for multi-project scheduling problems. The financial requirements of contractors working in a multiple project environment are addressed and investigated in this research. For model formulation, constraint programming (CP), which incorporates the techniques from mathematics, artificial intelligence, and operations research, is employed to solve the scheduling problem. The current study also presents an example involving three projects to illustrate model capability. The result shows that contractors can explicitly observe and specify cash flow at specific time points according to project progress, by identifying the amount and timing of individual inflow or outflow at the end of each period.