Abstract: This paper presented a new free piston expander-linear generator（FPE-LG） for small-scale organic Rankine cycle（ORC） waste heat recovery system. A FPE-LG experimental test rig was developed and a simulation model based on Matlab/Simulink was established. The simulation model was validated with respect to the experimental results at relatively high intake pressure and operating frequency. Further investigation on the motion characteristics and output performance of FPE-LG were conducted with relatively high intake pressure and operating frequency based on the simulation model. The results show that the intake pressure and operating frequency have a great effect on the motion characteristics and output performance. The peak power output is 676 W when the intake pressure, external load resistance, and operating frequency are 10 bar, 9? and 15 Hz, respectively.