In this paper, the temporal-spatial variation characteristics of wave velocity ratios of small earthquakes before the Heze earthquake with Ms 5.9 are studied. It is found that there is a concentrative area of low value anomaly of wave velocity ratios near Heze for two years. When the wave velocity ratio rises again up to the maximum value in the concentrative area, the activity of small earthquakes becomes quiet. Then the low values of wave velocity ratios extend toward outer. When the wave velocity ratios of small earthquakes in the periphery change to the minimum value, and then the values rise again to normal, the mainshock occurred in the concentrative area of low values. Before the mainshock, the low values of wave velocity ratios last three years, restoring to the normal values until about 15 days prior to the mainshock. Finally, some relative problems about the wave velocity ratio anomaly are discussed.