The heterogeneity of the permeability distribution in clastic rock reservoirs is the objective factor that directly affects the efficiency of petroleum production. The paper proposes that the permeability distribution in reservoirs has the fractal character, with its fractal dimension ranging between 2 and 3. Study on the examples suggests that fractal dimension can describe the heterogeneity of the permeability distribution and that its value increases with increasing heterogeneous degree. Fractal dimension also reflects the impact of deposit energy distribution and diagenesis on the permeability distribution. Fractal dimension will be an important parameter of studying the mathematical and genetical characters of the permeability distribution in clastic rock reservoirs. The study of the relationship between fractal dimension and petroleum engineering parameters is of practical significance.