Special concrete specimens were made of coarse aggregate consisted of crushed limestone whose particle diameters ranged from 5 to 7mm. The uniaxial and biaxial tensile strength testing results were obtained by material tests using mechanical biaxial stretching equipment; meanwhile, theoretical values were calculated using the formula derived from the Hill Theory. The results show that the specimens’ biaxial tensile strength is 15%-30% lower than that of uniaxial. Theoretical values fit well with testing results, with maximum difference lower than 11%. This conclusion is of great significance to the design of plate and shell concrete structure which is used under complex stresses.