Aimed at the grid system being more in failure and existing failure detection algorithms being not able to satisfy the unique requirement of grids, it was presented to a kind of adaptive failure detection algorithm in this paper. According to the characteristics of grids and the small world theory, the authors established a sort of small world based grid system model and a sort of failure detection model. By means of combining unreliable fault detection method with heartbeat strategy and grey prediction model, it was designed to dynamic heartbeat mechanism, and presented to the adaptive failure detection algorithm for grid systems further. Experimental result demonstrates that it is valid and effective in method, and it can be used for fault detection under grid environment.