To improve the spectrum utilization rate and reduce the establishment delay and blocking rate of an optical path, a joint-optimization routing spectrum allocation (CODS-RSA) algorithm based on the delay and spectrum utilization rate is proposed herein. The CODS-RSA algorithm establishes an optical connection request service database by calculating a control model, a spectrum bit diagram, and an optimal allocation algorithm during a preliminary calculation period. Then, the CODS-RSA algorithm performs routing spectrum allocation based on the optical connection request service database and real-time update calculation. The simulation results show that preliminary calculations of the CODS-RSA algorithm reduce the optical path’s establishment delay; the allocated spectra of optimal allocation algorithm and the spectrum bit diagram improve the spectrum utilization; the service request’s blocking rate is relatively reduced as well.