A multifunctional true triaxial rock drilling test system and method; rock cores are respectively taken from a plurality of drilling holes on the same test piece, uniaxial test and triaxial test are respectively performed on these rock cores to obtain multiple groups of mechanical property parameters, multiple groups of drilling parameters are obtained according to a multifunctional true triaxial rock drilling tester that can directly measure the drilling parameters, relational expression between mechanical property parameters of rock mass and the drilling parameters is established, and mechanical property parameters of rock mass can be obtained just by detecting the drilling parameters of the rock mass through the relational expression. The multifunctional true triaxial rock drilling tester is preset test device, has function of performing triaxial loading on the test piece, and can simulate drilling process of drilling rig in a three-way confining pressure state in underground engineering of the test piece.