Under the low oil prices，much attention has been paid to radial drilling because of its low cost，short time and high efficiency. In view of the present situation of its complex fracture system，various types，great difficulty and poor effect of conventional development of the remaining oil in the high position of the fault block reservoir，the radial drilling technology was proposed to realize the effective exploitation of the remaining oil. The productivity prediction model for radial drilling was built and its accuracy was verified by coupling of the expression of radial drilling potential and the equation of flow in the hole which was established according to the principle of mirror reflection and potential superposition. The results show that the radial drilling can realize the economic and effective exploitation of the remaining oil in the high position of the fault block reservoir. The error between the calculated oil production of the new model and that of the numerical simulation is less than 10%，which shows that the formula can be used to predict the productivity of the fault block reservoirs that use radial drilling technique. The larger the radial drilling length is，the better the simulation effect is. The effect of vertical multi-branch development becomes better with the increase of reservoir thickness. With the increase of reservoir thickness，the oil production index decreases gradually，and the radial drilling technique is more suitable for the thin oil reservoir exploitation.