Compared with plastic concrete(PC), behavior of stress strain strength of recycled plastic concretes(RPC) was studied by uniaxial, conventional triaxial and true triaxial compression tests. The strength failure criterion based on spatial octahedron stress was established. The results show that the Coulomb failure criteria is applicable for recycled plastic concretes, while the cohesion is less than that of plastic concretes, the internal friction is similar. Failure modes change from strain softening under uniaxial stresses to strain plasticizing under triaxial stresses, and it is more ideally plasticizing with the more lateral pressures. The maximum volumetric strain occurs in the three kinds of tests, and it becomes higher with the lateral pressure. The crack resistance of recycled plastic concrete is higher than that of plastic concretes, and increases with lateral pressures.