High construction-cost is one of the barriers that limited the developments of wave energy utilization. Integrating wave energy converters (WECs) into other marine structures may reduce the construction cost of WECs effectively. In this paper, an integrated system with a medium array (11 devices) of heaving point absorber WECs (PAWECs) arranged at the weather side of a fixed pontoon-type structure is proposed. The hydrodynamics of the PAWECs are investigated numerically by using higher-order boundary element method (HOBEM) code package (i.e., WAFDUT), which is developed based on linear potential flow theory. The hydrodynamic performance (including interaction factor, wave exciting force and heave response) of the WEC array with the rear pontoon is investigated with focus on the influence of the spacing between the WEC array and the pontoon (WEC-pontoon spacing). For sake of comparisons, the results corresponding to the isolated WEC array, i.e., without the pontoon, are presented. Results show that the performance of the pontoon-integrated WEC array performs better than that without the pontoon.