Hot molten salt storage tank is the key energy storage equipment in solar thermal power stations. The accidents of similar equipment indicates that there is a risk of periodic cracking for storage tanks based on general strength design specifications. Based on the high-temperature structural strength design theory, risk-informed design methods were introduced to a 100 MW CSP plant. Quantitative control indicators for risk sources were reversely calculated. The results show that when the equivalent friction coefficient of bottom plate is greater than 0.65, the tank could have ratchet damage during heat-up stage. When the thickness of sand layer is greater than 60 mm, the sidewall of the storage tank could be instantaneously fractured. The range of temperature fluctuation should be limited between-20℃ and +25℃ to avoid high cycle fatigue fracture and buckling. Meanwhile, it is recommended to appropriately increase the center height of the tank bottom（<29 mm） to prevent thermal stress failure.