Abstract: A flat installed anti cracking floor splice bar with buckle fixation, both the side of the long and short borders of the splice bar plate body (1) have splineway (11), and the other side of the splice bar has rabbet (12), therein, the upper slot surface of splineway (11) is paralleled to the upper surface of the rabbet (12) which are located in the same height. The V type groove (115) and protuberance (123) are mounted in the underside slot surface of splineway (11), furthermore, the front end of the protuberance (123) is inosculated with the outside of the splineway (11) so as to formed the anti self locking incline which is formed the first angle (?) with the upper surface of the splice bar, and the rear end of the protuberance (123) is inosculated with the outside of the V type slot (115) so as to formed the self locking incline which is formed the second angle (?) with the upper surface of the splice bar.