Along with deterministic size effect theory statement, Weibull distributed size effect has been neglected generally. The author believes that, deterministic size effect is not established to the basic strength index of plain concrete without notches. Definite size effect has an application limitation on the large-size zone. The most recent development of size effect is the fracture size effect theory based on probability in modern times. As a result of stress concentration caused by the notches, failure mechanism is bond to be affected. Therefore, the existing fracture theory needs to be tested. Meanwhile, the weakest chain link theory of material unit is still used in the existing statistics energy size effect model, which still needs to fix Weibull parameter m. Through more than 1000 dates of 24 groups of various kinds of concrete cube compressive strength and splitting tensile strength statistical tests in the recent years by our project group, the article has analyzed the statistical characteristics of basic strength of concrete and its influencing factors. Regression statistical analysis on shape and scale parameters of Weibull distribution has been studied.