The rapid development of ports has brought great economic benefits to the region; however, it has also caused some ecological risk. Ecological risk assessment is the basic of the risk management. In order to enhance the risk management, ecological risk assessment is necessary, which is of fundamental importance to set controlling plans. In the present study, we take Tianjin Port as a case, and firstly use the relative risk model (RRM) to evaluate the ecological risk of the port. Tianjin Port is located in the Bohai Bay. This bay is a semi-enclosed bay, which is located in the western region of Bohai Sea in northern China. The Bohai Bay has been conditioned strongly, historically, by different anthropogenic pressures. In particular, during the recent three decades, with rapid industrialization and urbanization, the seashore area of Bohai Bay were reclaim for agriculture and aquiculture, and subsequent occupation of those areas for urban, industrial and port developments have provoked a dramatic reduction in size. Based on the RRM, we divide the Tianjin port into four risk units, including Beijiang Wharves, Nanjiang Wharves, Dongjiang Wharves, and Lingang Wharves. Two main habitat types (the coastal wetland and nearshore waters), two risk sources (Transportation and wharves), three kinds of ecological receptors (zoobenthos, phytoplankton, and zooplankton), were identified and to calculate the comprehensive ecological risk value. In the present study, the risk grades can be classed five grades. When the risk value rang from 0 to 2, is the weak risk. The value is from 2 to 4 is the low risk, 4 to 6 is the middle risk, 6 to 8 is the relatively high risk, and more than 8 is the high risk. The results showed that the risk of the transportation is higher than the wharves risk in the two risk source. The risk of the nearshore water is higher than the coastal wetland in four risk units. For the risk of the ecological receptors, we found that the zoobenthos was significantly more influenced than both the phytoplankton and zooplankton. There were three class risk grades in the present study. The first grade is the Beijiang Wharves, with the risk value of 10.77, belonging to the high risk area. Nanjiang Wharves is belonged to the relatively high risk area, with the risk value of 6.12. The risk value of Dongjiang Wharves, and Lingang Wharves was 4.76 and 4.92, respectively, suggesting that they were in the grade of the middle risk level.