Abstract: To analyze its dynamic characteristics, the starting process and stable operation of a compression ignition free-piston linear alternator (FPLA) were simulated with numerical methods, and the load and frequency characteristics of FPLA were analyzed. The results indicate that, compared with crankshaft-driven engine, free-piston engine (FPE) has greater acceleration around its top dead center, which leads to slower compression stroke and faster expansion stroke. With the increasing of power output of FPLA, the in-cylinder peak pressure, compression ratio and indicated efficiency keep decreasing, while the load coefficient of linear alternator, peak electromagnetic force and energy input every cycle keep increasing. With the increasing of operating frequency, the load coefficient of linear alternator keeps decreasing while the averaged piston speed, indicated efficiency and power output keep increasing, and the maximum electromagnetic force is reached at certain frequency in between.