The invention provides a method for detecting the shearing strength of an interlayer bonding surface of rock filled concrete of constructional engineering. After a test piece is manufactured through excavation in a rock filled concrete dam or foundation of the constructional engineering, vertical loading and horizontal loading are applied to the test piece gradually and respectively, the linear regression coefficient is determined according to the computational formulas of normal stress and shearing strength on a shearing surface, and the shearing strength of the interlayer bonding surface of the rock filled concrete dam can be calculated. According to the method, the test piece is excavated on a structural member entity, the test piece is subjected to shearing strength test by a jack, force applied to the test piece is pure shearing force, the concrete failure surface is consistent to the direction of the anti-shearing force, the influence factors in a testing process are reduced, the testing precision is improved and the testing process is simple and easy.