Abstract: Time-based periodic inspection method frequently results in disrepair or over-repair for large-scale oil tank, therefore, how to rationally determine the internal inspection period for oil tank is of significance to balance the running requirements and inspection investments for oil tank. RBI technology-based prediction method of internal detection cycle is proposed. Researches have shown that predicted internal detection cycle for storage tanks increases with the expansion of acceptable risks. A method for determining acceptable risks of crude storage tanks is proposed to determine 3.54×10⁴ as the acceptable risk value of crude storage tanks. For storage tanks with relatively serious corrosion and short internal detection cycle, Gumbel-based prediction method is more conservative than the RBI-based method. Compared with the RBI technology-based prediction method of internal detection cycle, domestic standard SY/ T 5921-2000 is relatively conservative. Therefore, it is recommended to use the RBI technology for determining the internal detection cycle of crude tanks.