A panel interlocking structure for adjacent panels of knock down, panel-based furniture, comprising interlock assemblies and connecting panels. Each interlock assembly consists one interlock tube, at least two cubical nuts and at least two interlock bolts. To form the interlock assembly, on a predetermined lengthen rectangular face of the interlock tube, via its corresponding predrilled trans-passing holes, fasten a predetermined number of the interlock bolts into the corresponding tread holes of the cubical nuts positioned inside the interlock tube, with each groove end of the interlock bolt positioned outwardly. Each connecting panel consists one cam lock side and two connection ends. Through the interlocking hole on the predetermined connection end of the connecting panel, the groove end of each interlocking bolt on the interlock assembly is inserted into the corresponding opening of the rotatable cam lock disposed in the dead end hole on the cam lock side of the connecting panel, and securely engages with the connecting panel by fastening the rotatable cam lock, thus thrusting engage forces to the groove end of each interlock bolt on the interlock assembly. All connecting panels are inter-connected via number of interlock assemblies. The invention provides improved durability, enhanced mobility, design-it-yourself capacity, as well as composition expandability for knock down, panel based furniture.