The risk of an enterprisepsilas optimum decision is one of the most important contents of the enterprise's risk decision. However, the most effective factor that may influence its optimum stock decision is the risk produced by the market practical demand. According to the micro-economy principal on market demand, connecting with methods of risk analysis, this paper tends to set up a risk index system and produce a model of risk evaluation through probing into all kinds of typical market demanding and the possible risks and effects on its optimum stock decision.