The invention provides a method for realizing a four-bit carry lookahead adder circuit based on DNA strand displacement, which comprises the following steps: researching a DNA strand displacement reaction principle based on DNA strand displacement reaction, designing a model based on DNA strand displacement, realizing logic exclusive-OR operation, and designing a biogenic circuit model on the basis of the logic exclusive-OR operation; designing a biochemical circuit of a four-bit carry lookahead adder based on a biochemical logic gate, and using Visual DSD software for carrying out simulationanalysis on the logic circuit. The carry bits of all the bits in the four-bit carry lookahead adder are generated at the same time and do not influence one another, and although the circuit structureis complex, the operation speed is higher. According to the invention, the dynamic behavior of the logic circuit of the four-bit carry lookahead adder is verified, and the reasonability and effectiveness of the circuit are proved. A basic theoretical basis is provided for constructing a more complex logic operation circuit in the future, and the development of the biological computer is promoted,so that the reliability of the logic circuit of the biological computer is improved.