This paper models road traffic demand of container trucks in a Chinese container port. The model is helpful for road planning and traffic management in the port. First, we analyze the attributes of road traffic in the port, to distinguish the differences between port area traffic and surrounding urban area traffic. It is found that port area traffic is generated from vessel operations and fluctuates corresponding to two major factors: operation time schedule and the truck arrival pattern within an operation time window. Since the first factor is available from terminal operators, the truck arrival pattern is the key for modeling port area traffic demand. Second, we conduct a comprehensive survey to collect truck traffic and vessel operation data, which is used to explore the probability distribution of truck arrivals during the consolidation periods. Third, we develop a traffic demand model based on the probability distribution with unknown parameters, and modify this model by taking the effects of some external factors into account. At last, we estimate the parameters with the collected data, and the result indicates that this traffic demand model has a high quality of estimation especially for peak traffic times.