circular saw blade the track of the circular saw blade defines with the bearing face 34 of the fence 30 a predetermined contained angle this contained angle is indicated subject to the pointer 22 at the worktable 20 and the graduations 12 on the surface of the machine base 10 this contained angle is referred hereinafter as u201c cutting angle u201d the rotary worktable positioning structure of the present invention is installed in the front side of the worktable 20 comprising a first positioning unit 60 and a second positioning unit 70 the first positioning unit 60 provides a stepless positioning effect i e allowing the worktable 20 to be positioned in any non particular cutting angle the second positioning unit 70 provides a rapid positioning effect to have the worktable 20 be positioned in one of a number of predetermined cutting angles for example 15 degrees 30 degrees etc the structure and operation of the first positioning unit 60 are described at first as follows referring to fig3 and 4 the worktable 20 has a forwardly protruding mounting frame 24 the mounting frame 24 comprises two wing panels 241 arranged in parallel and a transverse panel 242 connected between the wing panels 241 each wind panel 241 has a first through hole 243 and a second through holes 244 for the passing of a first pivot pin 26 and a second pivot pin 28 respectively one.