Proportionality in the narrower sense can cause the abuse of discretion and inadequate measurement of benefits and results-oriented analysis, so we should make proportionality in the narrower sense more specific to limit balancing. The concretization of proportionality in the narrower sense can be mainly divided into two modes. One is the mathematical model, from the perspective of the balancers; the other is the discourse mode, from the perspective of the litigants. The essence of proportionality in the narrower sense is the judgment of the necessity of purpose. Its functions are to protect human rights and to make sure that the whole social welfare is promoted. In order to eliminate the irrationality of proportionality in the narrower sense as much as possible, we should construct a new concretization mode from the common perspective of the balancers and the litigants: we should use cost-benefit analysis and the formula of the equilibrium to calculate the proportional numerical value of the least restrictive means which can promote public interest and cause damage, and then balance whether the least restrictive means complies with proportionality in the narrower sense according to the formula of the equilibrium.