[Objectives] To design the reasonable cost and efficient performance of mooring systems of WECs, it is necessary to investigate effects of mooring systems on dynamic response of wave energy converters. [Methods] A two-body floating point absorber is chosen as the investigated example of wave energy converters (WECs). The open-source WEC-sim and MoorDyn codes are used to design two types of mooring systems of the WEC. One is the mooring system, which uses chains. The other is the hybrid mooring system, which uses chains and polyester ropes. By performing time-domain analysis for the WEC with different mooring lines, the displacements of WEC，the power take-off (PTO) response and the tensions of mooring lines are obtained, respectively. [Results] By analyzing the results, the following phenomena can be found:(1) The effect of mooring systems on the displacement response of the floater is small, but the effect of mooring systems on the response of the spar body is obviouse; (2)effects of mooring systems on PTO response of the WEC are almost the same for the linear damper PTO model; (3) the line tensions of the hybrid mooring system are lower than the corresponding tensions of the chain mooring system. [Conclusions] These investigations have reference value for better designing mooring systems for WECs.