Through tax cuts, monetary contraction, relaxation of market access, reduction of administrative intervention and other means, the supply side reform can improve the efficiency of supply.At the first stage, due to governments protection of traditional industries and stimulation of emerging industries, employment will improve rapidly. With the deepening of reform, market mechanism will gradually show its power and traditional industries will withdraw violently. As to emerging industries, new enterprises will face the survival test and the risk of unemployment will be exposed. Only when the emerging industries really rise will the employment meet the upward point. Based on the experience of China, the United States, Britain, Germany and other countries, we generally verify the above judgment. This paper reminds us that the supply side reform may face a great challenge, especially in its medium term. Chinas employment may meet with a test period of pains. We should be well prepared in this regard.