For the purpose of improving the quality of optical network communication ,the paper studies the dy- namic spectrum allocation method based on crosstalk perception in time to improve the dynamic spectrum allocation effect. By calculating the crosstalk value of the optical network ,a dynamic spectrum allocation model of the optical network is established with the minimum crosstalk as the objective function ,the inter-core crosstalk generation condi- tion constraint ,and the inter-core crosstalk threshold constraint as the constraint conditions ; In quantum genetic algo- rithm ,chaos optimization algorithm is introduced to obtain improved quantum genetic algorithm to avoid falling into lo- cal optimal solution ; The improved quantum genetic algorithm is used to solve the dynamic spectrum allocation model ,and the dynamic spectrum allocation scheme of optical network with minimum inter-core crosstalk is obtained. The ex- periment shows that this method can effectively complete the dynamic allocation of optical network spectrum and reduce the inter-core crosstalk of optical network under different optical network types. Under different network loads ,the op- tical network bandwidth blocking rate of this method is 0. 17 lower ,and the spectrum utilization rate exceeds 0. 13.