Abstract: The experimental β-—decay lives of nuclei far from stable line are systematically analyzed and an exponential law between β-decay half-life and the nucleon number(Z,N) of parent nuclei far from the β-stable line is discovered.Based on theoretical analysis,a new formula with four parameters is proposed to describe the β-—decay half-lives of nuclei far from the β-stable line.Experimental data are well reproduced by the formula.In addition,by using this formula,the β-—decay half-lives of some unknown nuclei are calculate and predicted.