A building block structure includes a joint adaptor unit and at least one connection bar. The joint adaptor unit includes one or multiple joint adaptors, each of which includes at least one screwing connection end that includes a right/left-hand combined threaded hole formed therein. The right/left-hand combined threaded hole includes multiple right-handed screw troughs and multiple left-handed screw troughs that are alternately arranged. The connection bar has one end having multiple spaced right-handed external threads and an opposite end having multiple spaced left-handed external threads. As such, when the connection bar is rotated in a given direction, the right-handed external threads and the left-handed external threads are simultaneously screwed into the right/left-hand combined threaded holes of two oppositely facing joint adaptors. Through rotation in an opposite direction, the right-handed external threads and the left-handed external threads are simultaneously disengaged from the right/left-hand combined threaded holes.