The invention relates to a safe and environment-friendly method for protecting storage tanks to mainly solve the problems that in the prior art, the gas consumption of nitrogen protection is excessively large, cost is high, and sulfur-containing gas and other peculiar smell gas are hard to treat. According to the safe and environment-friendly method for protecting the storage tanks, the gas produced by liquid in the storage tanks enters a compressor (18) through a main gas pipe (19) and an inflation pipe (21), the gas is pressurized by the compressor (18) and stored in a buffering tank (5) to serve as one part of positive-pressure protection gas, when the gas stored in the buffering tank (5) cannot meet the positive-pressure protection of all storage tanks, the nitrogen from a nitrogen inlet pipeline (22) is used for performing supplementation, and when the pressure stored in the buffering tank (5) exceeds the designed pressure, the residual gas is sent to a torch or combustion furnace through a torch or combustion furnace leading pipeline (22), the problems are well solved through the technical scheme, and the method can be used in storage tank protection.