Cuttings are important evidence for the formation research, and there is a significant correlation between rock drillability and fractal dimension in Lab, but the geometric characteristics and particle size distribution of cuttings are affected by multiple factors during the drilling process, particle size distribution is different for cuttings obtained under different conditions. According to fractal theory, the cuttings of different engineering and geological conditions are analyzed to sum up the influence and influence degree of various factors to fractal law of cuttings. The results show that the cuttings particle size distribution has good fractal features; the cuttings fractal dimension is conform to the real drilling situation; and equiprobable breaking Pc is one of the parameters to judge drilling efficiency, Pc value can be reduced by adjusting drilling parameters to improve ROP.