Conclusions of researches on the relationship between concrete splitting tensile strength and axial tensile strength are inconsistent. To study the relationship, splitting tensile test with loading strip width ranging from 5mm-20mm and axial tensile test were conducted. The size of splitting tensile test cylindrical specimens is 150mm×300mm and size of the axial tensile test specimens is 100mm×100mm×550mm. Based on cohesive crack model of fracture mechanics theory, this paper builds a regression equation between fts/ft and D/L_ch. The parameter's values of the formula are also given. It can be proved that the formula is acceptable and can be applied in design and detection of massive concrete structures.