Yield and failure properties on the deviatoric plane for geotechnical engineering materials under three-dimensional stress state are characterized by anisotropy, which can not be reflected by most classical strength criteria. This paper extended the egg-shaped function from the meridional plane to the  plane and proposed the egg-shaped strength criterion for the deviatoric plane. Only 2 parameters α2 and β are required, which represent the curvature of egg-shaped function and the ratio of triaxial tensile strength to triaxial compressive strength, respectively. First of all, the feasibility of the egg-shaped function as yield/failure envelopes of deviatoric plane was mathematically demonstrated. Then the validity of the egg-shaped criterion was then analyzed and discussed combined with the results of several true triaxial tests. The numerical results show that the egg-shaped function can well simulate the strength envelopes with different geometric types depend on the defining parameters. When β is well determined, the egg-shaped function can successfully reproduce the test results as well as some other g(θ) expressions including the SMP criterion. And as α2 approaches 0, the egg-shaped strength envelope tends to be consistent with the SMP criterion. When it approaches 1, the egg-shaped strength envelope tends to be consistent with that of the Mohr-Coulomb criterion.