B610CF steel is a newly steel, and is widely used. The test data of tensile strength for B610CF steel is fitted several kinds of probability statistical models. In this paper, the correlation coefficient method and K-S method were used to test the fitting effects. It is concluded that three-parameter Weibull distribution is the optimal distribution for the test data, and the security tensile strength of 48mm B610CF steel is 627.54MPa under the condition of 99.9% reliability. Through the study of tensile strength confidence interval for B610CF steel, it is obtained that confidence interval is [601.47MPa, 644.86MPa] under the condition of 99.9% reliability and 80% confidence level. The results are important for the structural reliability analysis of B610CF steel.