Abstract: According to the characteristic that irrationality of decision making is only considered and risk attitude of decision-maker is not distinguished when function parameters of value prospect theory is selected,the form of value function is modified and the range of function parameters is expanded based on utility curve.The function uses the utility curve method which distinguishes the risk attitude of decision-maker according to curve's figure for reference,and the conclusion that curve's figure of value function is related with risk attitude of decision-maker is elicited according to existed experimental data.This provides certain theoretical basis for selecting value of parameters in value function.The calculation example shows that the method is convenient for selecting parameters,and the decision-making result is stable and valid,and besides,the influence of various reference points on the result of risk decision making is bigger than various risk attitudes,thus their selection needs highly caution in actual decision-making.