Abstract: Germany is one of the earliest counties to establish unemployment security system. With changes in economic situation and social environment, especially the unification in 1990, Germany has continually adjusted unemployment insurance systems since the late 19th century. It's worth noting that the "Employment Promotion Law" in 1969 and the Harz Reform during 2002—2005 played important roles in these adjustments. The article reviews the development of the unemployment insurance system in Germany, and results show that the unemployment rate of Germany gradually decreased after 2002, but it is not clear whether this decrease was caused by the revision of the current unemployment insurance policy because of the time lag of the policy implementation. The effect of the German unemployment insurance system still needs time to test.