Project profit and cost control are important factors affecting profitability. Most academic research is mainly focused on the theoretical study, less on the practical analysis. In this paper, case study method was used to analyze the data taken from a total of 241 software Projects of the company "p" in four years to explore the relationship among project cost, quantity and profit with the aim to find the key affecting factors of the cost and key of the performance. In this study we demonstrated that the average cost of all project manpower is 73.4% of the total cost. The average costs of Product (PD), Monthly Rent (MR), Maintenance (MA), and Project (PJ) and human resources of the profitable project are 10.5%, 17.8%, 24.8%, 36.5%, respectively. Product (PD) is more profitable because of the human resources cost is lower. Profit is largely influenced by the Regulation, thus company is requested to pay special attention to the changes of the Regulation.